421 
 
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 NOAA Technical Report 
 
 Circular 421 
 
 Larval Development of 
 Shallow Water Barnacles of 
 the Carolinas (Cirripedia: 
 Thoracica) With Keys 
 to Naupliar Stages 
 
 William H. Lang 
 
 February 1979 
 
 U.S. DEPARTMENT OF COMMERCE 
 
 National Oceanic and Atmospheric Administration 
 
 National Marine Fisheries Service 
 
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^MMO,s, V// 
 
 «/r. 
 
 ^ r ^IH\ 01 *° 
 
 NOAA Technical Report NMFS Circular 421 
 
 Larval Development of 
 Shallow Water Barnacles of 
 the Carolinas (Cirripedia: 
 Thoracica) With Keys 
 to Naupliar Stages 
 
 William H. Lang 
 
 February 1979 
 
 U.S. DEPARTMENT OF COMMERCE 
 
 Juanita M. Kreps, Secretary 
 
 National Oceanic and Atmospheric Administration 
 
 Richard A. Frank, Administrator 
 
 Terry L Leitzell, Assistant Administrator for Fisheries 
 
 National Marine Fisheries Service 
 
The National Marine Fisheries Service (NMFS) does not approve, rec- 
 ommend or endorse any proprietary product or proprietary material 
 mentioned in this publication. No reference shall be made to NMFS, or 
 to this publication furnished by NMFS, in any advertising or sales pro- 
 motion which would indicate or imply that NMFS approves, recommends 
 or endorses any proprietary product or proprietary material mentioned 
 herein, or which has as its purpose an intent to cause directly or indirectly 
 the advertised product to be used or purchased because of this NMFS 
 publication. 
 
CONTENTS 
 
 Page 
 
 Introduction 1 
 
 Materials and methods 1 
 
 Larval development of barnacles . 3 
 
 Definition and diagnostic characters 3 
 
 Larval descriptions 7 
 
 Balanus venustus Darwin 7 
 
 Balanus eburneus Gould 9 
 
 Balanus amphitrite amphitrite Darwin 13 
 
 Balanus improvisus Darwin 14 
 
 Balanus subalbidus Henry 17 
 
 Balanus trigonus Darwin 18 
 
 Conopea galeata (Linnaeus) 19 
 
 Chelonibia patula (Ranzani) 19 
 
 Chthamalus fragilis Darwin 22 
 
 Octolasmis muelleri (Coker) 24 
 
 Lepas spp 25 
 
 Nauplius SC 27 
 
 Keys to the barnacle larvae of the Carolinas 29 
 
 Assigning stages 29 
 
 Species identification of nauplii 31 
 
 Cyprids 36 
 
 Discussion 36 
 
 Acknowledgments 37 
 
 Literature cited 38 
 
 Figures 
 
 1. Descriptive terminology of barnacle larvae 4 
 
 2. Setation formulae for the mandible of stage IV Balanus eburneus nauplius - 5 
 
 3. Examples of barnacle larvae setal types 6 
 
 4. Diagnostic morphological features of balanomorph nauplii at each stage 8 
 
 5. Balanus venustus. Shield outlines 9 
 
 6. Balanus venustus. Naupliar antennule and mandible 10 
 
 7. Balanus venustus. Naupliar antenna 11 
 
 8. Balanus venustus. Abdominal process and labrum 12 
 
 9. Balanus eburneus. Shield outlines and abdominal process 13 
 
 10. Balanus amphitrite amphitrite. Shield outlines, cyprid carapace profile, and abdominal pro- 
 
 cess 14 
 
 11. Balanus improvisus. Shield outlines 15 
 
 12. Balanus improvisus Antenna, antennule, labrum, and abdominal process 16 
 
 13. Balanus subalbidus. Shield outlines, labrum, and abdominal process 17 
 
 14. Balanus trigonus. Shield outlines 18 
 
 15. Balanus trigonus. Antenna and mandible 19 
 
 16. Balanus trigonus. Abdominal process and labrum 20 
 
 17. Conopea galeata. Shield outlines, labrum, dorsal shield spines, and abdominal process . . 21 
 
 18. Chelonibia patula. Egg, shield outlines, and carapace profile 21 
 
 19. Chelonibia patula. Antennules 22 
 
 20. Chelonibia patula. Antennae 23 
 
 21. Chelonibia patula. Mandibles 24 
 
 22. Chelonibia patula. Abdominal process and labrum 25 
 
 23. Chthamalus fragilis. Shield outlines, lateral profile, and carapace outline 26 
 
 24. Chthamalus fragilis. Antennule, antenna, and mandible 26 
 
 25. Chthamalus fragilis. Abdominal process and lateral profile 27 
 
 26. Chthamalus fragilis. Labrum 27 
 
 27. Octolasmis muelleri. Shield outlines 28 
 
 iii 
 
28. Octolasmis forrestii. Shield outlines 28 
 
 29. Octolasmis forrestii. Antennule, antenna, mandible, and labrum 29 
 
 30. Lepas pectinata. Shield outlines and lateral profiles, abdominal spines, labrum, antennule, an- 
 tenna, and mandible 30 
 
 31. "Nauplius SC." Shield outlines and lateral profiles 31 
 
 32. "Nauplius SC." Antennule, antenna, and mandible 32 
 
 33. Stage II nauplii of Balanus amphitrite -complex species common in Carolina waters ... 32 
 
 34. Stage II nauplii of barnacle species found in Carolina waters 33 
 
 35. Morphological features of Carolina barnacle nauplii 35 
 
 36. Cyprids of South Carolina 36 
 
 Tables 
 
 1. Thoracican Cirripedia of the South Carolina coast 1 
 
 2. Studies on barnacle larval development 2 
 
 3. Setal types of cirriped nauplii 5 
 
 4. Typical setation counts for balanid nauplii 8 
 
 5. Setation formulae for nauplii of Balanus venustus 9 
 
 6. Setation formulae for nauplii of Balanus eburneus 13 
 
 7. Size of Balanus eburneus and Balanus amphitrite larvae 15 
 
 8. Setation formulae for nauplii of Balanus a. amphitrite 15 
 
 9. Setation formulae for nauplii of Balanus trigonus 18 
 
 10. Setation formulae for nauplii of Chelonibia patula 22 
 
 11. Setation formulae for nauplii of Chthamalus fragilis 26 
 
 12. Structure of the Octolasmis lowei-complex 27 
 
 13. Setation formulae for nauplii of Octolasmis muelleri 29 
 
 14. Setation formulae for nauplii Y ' 31 
 
 15. Size ranges of barnacle nauplii obtained by laboratory rearing and plankton samples ... 34 
 
 16. Size of barnacle cyprids reared in the laboratory 34 
 
 17. Setal counts for the antennae of stage VI nauplii of some barnacle species 37 
 
 IV 
 
Larval Development of Shallow Water Barnacles of 
 
 the Carolinas (Cirripedia: Thoracica) With 
 
 Keys to Naupliar Stages 1 
 
 WILLIAM H. LANG 
 
 ABSTRACT 
 
 The report includes an introduction to structure, descriptions, and illustrated keys to the barnacle 
 larvae of Georgetown, S.C. Descriptions of 13 species are based on both laboratory reared and field 
 specimens. The complete naupliar development of Chelonibia patula, Chthamalus fragilis, Balanus 
 venustus, Balanus subalbidus, Octolasmis forrestii, and an unknown species, "nauplius SC," is 
 described for the first time. 
 
 INTRODUCTION 
 
 The abundance and ability of barnacles to settle on 
 virtually any solid substrate has made them a target of 
 numerous detailed studies (see Newman and Ross 1976). 
 Although the biology of many adult barnacles is rela- 
 tively well studied, little information exists on the larval 
 biology of cirripeds. This is particularly true of temper- 
 ate and tropical species, as is evident by the limited in- 
 formation available for cirriped larvae along the south- 
 eastern coasts of the United States. Of over 25 species of 
 thoracican cirripeds known to occur in South Carolina 
 waters (Table 1), life histories are known for five species 
 (Table 2) and the larvae of only two species, Balanus am- 
 phitrite amphitrite and Balanus eburneus, have been 
 studied regionally (Costlow and Bookhout 1957, 1958). 
 
 This study was initiated to provide missing larval 
 descriptions of common southeastern barnacle species 
 and to construct a key for field identification of barnacle 
 nauplii of coastal Carolina waters. In addition, some 
 changes in descriptive terms and setation formulae are 
 proposed. 
 
 MATERIALS AND METHODS 
 
 Adult barnacles were primarily collected in North In- 
 let and Winyah Bay near Georgetown, S.C. Of 11 species 
 obtained in the Georgetown region (Table 1), larvae were 
 reared for 10 species. Additional material for compara- 
 tive purposes was collected at Pettaquamscutt Pond and 
 Narragansett Bay, R.I., or obtained from Belize, Central 
 America. Further details of collection sites and habitats 
 are described in the introduction to the larval descrip- 
 tions. 
 
 Various methods and diets were used to rear barnacle 
 larvae both to obtain material for descriptions and for 
 diet-temperature studies (Lang 3 ). In general, most de- 
 scriptive material was obtained using rearing methods 
 similar to those of Freiberger and Cologer (1966); how- 
 ever, antibiotics were not used and mixed algal diets 
 were employed. Larvae were obtained from adult bar- 
 nacles maintained in laboratory tanks and fed Artemia 
 
 'Lang, W. H. 1977. The barnacle larvae of North Inlet, South Caro- 
 lina (Cirripedia: Thoracica). Unpubl. Ph.D. Thesis, Marine Science 
 Program, Univ. South Carolina, Columbia, 179 p. 
 
 Table 1. — Thoracican Cirripedia of the South Carolina 
 coast. (From Zullo and Lang 1978.) 
 
 Suborder Lepadomorpha 
 
 Lepadidae 
 
 Lepas anatifera 
 
 L. anserifera 
 
 L. hilli 
 
 L. pectinata 
 
 Conchoderma auritum 
 
 C. virgatum 
 
 Scalpellidae 
 
 Scalpellum gibbum 
 
 Poecilasmatidae 
 
 Octolasmis hoeki 
 Octolasmis muelleri 
 Trilasmis spp. 
 
 'Contribution No. 188 of the Belle W. Baruch Library in Marine Sci- 
 ence, University of South Carolina, Columbia, SC 29208. 
 
 2 U.S. Environmental Protection Agency, Environmental Research 
 Laboratory, Narragansett, RI 02882. 
 
 Suborder Balanomorpha 
 
 Archeobalanidae 
 
 Acasta cyathus (?)' 
 Conopea galeata 
 C. merrilli 
 
 Glanaidae 
 
 Balanus a. amphitrite 
 
 B. calidus 
 
 B. eburneus 
 
 B. improvisus 
 
 B. reticulatus (?)' 
 
 B. subalbidus 
 
 B. trigonus 
 
 B. venustus 
 
 Chthamalidae 
 
 Chthamalus fragilis 
 
 Coronulidae 
 
 Chelonibia patula 
 
 C. testudinaria 
 Platylepas hexastylos 
 Stomatolepas elegans 
 
 '(?) = probable occurrence. 
 
Table 2.— Studies on barnacle larval development. Source of larvae: laboratory reared (r), plankton samples (p), or both (p/r). 
 
 Species 
 
 Source Stages 
 
 Locations and authors 
 
 Species 
 
 Source Stages 
 
 Locations and authors 
 
 Lepadomorpha 
 
 
 
 Scalpellum scalpellum 
 
 
 all 
 
 Pollicipes spinosus 
 
 
 all 
 
 P. mitella 
 
 
 all 
 
 P. polymerus 
 
 
 all 
 
 Ibla idiot ica 
 
 
 all 
 
 I. quadrivalvis 
 
 
 all 
 
 I. cumingi 
 
 
 all 
 
 Lepas fascicularis 
 
 P 
 
 all 
 
 Verrucomorpha 
 
 
 
 Verruca stroemia 
 
 p/r 
 
 I-VI 
 
 
 P/r 
 
 I-VI 
 
 Balanomorpha 
 
 
 
 (Chthamaloidea) 
 
 
 
 Chthamalus stellatus 
 
 P/r 
 
 I-VI 
 
 
 r 
 
 all 
 
 
 r 
 
 I- CI 
 
 C. dentatus 
 
 P 
 
 I-II 
 
 C. malayensis 
 
 r 
 
 all 
 
 Chamaesipho columna 
 
 r 
 
 all 
 
 C. brunnea 
 
 r 
 
 all 
 
 Euraphia aestuarii 
 
 P 
 
 I-VI 
 
 Euraphia depressa 
 
 r 
 
 I-VI 
 
 Octomeris angulosa 
 
 P/r 
 
 I-VI 
 
 (Coronulaidea) 
 
 
 
 Chelombia patula 
 
 r 
 
 i-m 
 
 C. testudinaria 
 
 P 
 
 i-ii 
 
 Tetraclita squamosa 
 
 r 
 
 all' 
 
 T. serrata 
 
 P 
 
 I-II 
 
 Tetraclitella karandei 
 
 r 
 
 all 
 
 (Balanoidea) 
 
 
 
 Acasta spongites 
 
 r 
 
 all 
 
 Chirona hameri 
 
 P/r 
 
 all 
 
 Conopea galeata 
 
 r 
 
 all 
 
 Eliminius modestus 
 
 P 
 
 all 
 
 Epopella plicatus 
 
 r 
 
 all 
 
 Semibalanus balanoides 
 
 P/r 
 
 I-VI 
 
 
 P 
 
 all 
 
 
 r 
 
 all' 
 
 Sweden (Kaufmann 1965) 
 New Zealand (Batham 1946a) 
 Japan (Yasugi 1937) 
 USA, west coast (Lewis 1975) 
 New Zealand (Batham 1946b) 
 Australia (Anderson 1965) 
 India (Karande 1974c) 
 Pacific (Willemoes-Suhm 
 
 1876; Bainbridge and 
 
 Roskell 1966) 
 
 p/r I-VI United Kingdom (Bassindale 
 1936) 
 
 United Kingdom (Bassindale 
 
 1936) 
 India (Daniel 1958) 
 Brazil (Lacombe 1973) 
 South Africa (Sandison 1954) 
 India (Karande and Thomas 
 
 1976) 
 New Zealand (Barker 1976) 
 New Zealand (Barker 1976) 
 West Africa (Sandison 1967) 
 France (LeReste 1965) 
 South Africa (Sandison 1954) 
 
 Brazil (Lacombe 1973) 
 India (Pillai 1958) 
 Japan (Hirano 1953) 
 South Africa (Sandison 1954) 
 India (Karande 1974b) 
 
 United Kingdom (Moyse 1961) 
 United Kingdom (Crisp 1962b) 
 USA, west coast (Molenock 
 
 and Gomez 1972) 
 United Kingdom (Knight-Jones 
 
 and Waugh 1949) 
 New Zealand (Barker 1976) 
 United Kingdom (Bassindale 
 
 1936) 
 North Atlantic (Crisp 1962a) 
 New York (Freiberger and 
 
 Cologer 1966) 
 
 Solidobalanus hesperius p/r I-VI 
 
 Boscia anglicum 
 
 T 
 
 all 
 
 Balanus balanus 
 
 P/r 
 
 all 
 
 
 P 
 
 all 
 
 Balanus crenatus 
 
 r 
 
 all 
 
 
 P/r 
 
 all 
 
 B. nubilus 
 
 P/r 
 
 I-VI 
 
 B. amphitrite amphitrite 
 
 r 
 
 all 
 
 
 P 
 
 I-II 
 
 
 r 
 
 all 
 
 
 P 
 
 all 
 
 
 r 
 
 all 
 
 
 r 
 
 all' 
 
 
 r 
 
 all 
 
 B. a. abicostatus 
 
 r 
 
 I-VI 
 
 B. eburneus 
 
 r 
 
 all 
 
 
 r 
 
 all 1 
 
 B improvisus 
 
 P 
 
 I-VI 
 
 
 r 
 
 all' 
 
 B. variegatus 
 
 r 
 
 all 
 
 
 r 
 
 all 
 
 B. pallidus stutsburi 
 
 P 
 
 I-VI 
 
 B. tngonus 
 
 r 
 
 all 1 
 
 
 P/r 
 
 I-VI 
 
 
 r 
 
 all 1 
 
 
 r 
 
 all 
 
 B. perforatum 
 
 P 
 
 all 
 
 
 P 
 
 all 
 
 Megabalanus algicola 
 
 P/r 
 
 all 
 
 M. t. tintinnabulum 
 
 t 
 
 i-ni 
 
 
 r 
 
 all 
 
 Washington (Barnes and 
 
 Barnes 1959b) 
 United Kingdom (Moyse 1961) 
 United Kingdom (Barnes and 
 
 Costlow 1961) 
 North Atlantic (Crisp 1962a) 
 California (Herz 1933) 
 United Kingdom (Pyefinch 
 
 1948) 
 Washington (Barnes and 
 
 Barnes 1959a) 
 Japan (Hudinaga and Kasahara 
 
 1942) 
 South Africa (Sandison 1954) 
 Brazil (Lacombe and Monteiro 
 
 1972) 
 India (Pillai 1958) 
 N. Carolina (Costlow and 
 
 Bookhout 1958) 
 Florida (Freiberger and 
 
 Cologer 1966) 
 India (Karande 1973) 
 Japan (Ishida and Yasugi 1938) 
 N. Carolina (Costlow and 
 
 Bookhout 1957) 
 Florida (Freiberger and 
 
 Cologer 1966) 
 United Kingdom (Jones and 
 
 Crisp 1954) 
 Florida (Freiberger and 
 
 Cologer 1966) 
 India (Daniel 1958) 
 India (Karande 1974a) 
 West Africa (Sandison 1954) 
 Japan (Hirano 1953) 
 South Africa (Sandison 1954) 
 Florida (Freiberger and 
 
 Cologer 1966) 
 New Zealand (Barker 1976) 
 United Kingdom (Groom 
 
 1894-95) 
 United Kingdom (Norris and 
 
 Crisp 1953) 
 South Africa (Sandison 1954) 
 Brazil (Lacombe 1973) 
 India (Daniel 1958) 
 
 'Primarily methodology/rearing papers with limited descriptions. 
 
 (day old nauplii through adults), rotifers, and mixed 
 algal cultures. Nauplii released from these populations 
 were concentrated using a narrow light beam and re- 
 moved with a pipette to 1 ^m filtered natural seawater 
 between 25 and 32V,.,. A double algal diet of Tetraselmis 
 suecia (TET) in combination with Monochrysis lutheri 
 (MON), Isochrysis galbana (ISO), Thalassiosira pseu- 
 donana (3H), or Skeletonema costatum (SKEL) was 
 used as food. Further details of rearing techniques and 
 diet results were described in Lang (1976, see footnote 3). 
 
 Drawings of larvae were made with a camera lucida. 
 When possible, freshly sacrificed larvae were used for in- 
 itial figures. The figures were verified using additional 
 material preserved in 70% ethanol or, more commonly, 
 Formalin and seawater. Measurements were made with 
 an ocular micrometer on unflattened preserved larvae. 
 Total length was measured from the anterior edge of the 
 cephalic shield to the tip of the dorsal thoracic spine. 
 Shield length was measured along the middorsal line 
 from anterior to posterior shield borders, exclusive of 
 
lateral or posterior shield spines. Width was measured at 
 the widest portion of the shield exclusive of frontolateral 
 horns and shield spines. Cyprid length was measured 
 from the anterior to posterior carapace margin. Cyprid 
 "width" or depth was measured as the greatest distance 
 from the dorsal to ventral carapace margins. 
 
 LARVAL DEVELOPMENT OF BARNACLES 
 
 The most common sequence of larval development for 
 thoracican cirripeds consists of six naupliar and one cyp- 
 rid stage. Using plankton reconstructions, Willemoes- 
 Suhm (1876) and Groom (1894-95) reported six naupliar 
 and one cyprid stage for both the lepadomorph Lepas 
 fascicularius and the balanomorph Balanus perforatum. 
 Herz (1933) reported eight naupliar stages from cultures 
 of Balanus crenatus larvae however, Bassindale (1936), 
 using both cultures and plankton material, found a 
 consistent pattern of six naupliar stages and one cyprid 
 stage for Verruca stroemia, Semibalanus balanoides, and 
 Chthamalus stellatus. Most studies since then have con- 
 firmed this pattern of larval development (Table 2). A 
 second study of B. crenatus yielded six naupliar stages 
 (Pyefinch 1948). Conclusive proof of the number of larval 
 stages was provided by the studies of Costlow and Book- 
 hout (1957, 1958). Counts of molts of the larvae of 
 Balanus eburneus and B. amphitrite amphitrite reared 
 individually in small compartments consistently yielded 
 the expected pattern of six naupliar and one cyprid 
 stages. 
 
 A remarkably uniform pattern of cirriped larval 
 development is evident. Adults release newly hatched 
 nauplii which, within a short time span, molt to stage II 
 nauplii. Further development (usually dependent on 
 proper diet) produces four additional naupliar stages and 
 the cyprid. The nonfeeding cyprid will select a sub- 
 strate, settle, and undergo final metamorphosis to a 
 juvenile. 
 
 Exceptions to this pattern of five planktotrophic 
 naupliar stages are known. Nilsson-Cantell (1921) re- 
 viewed rather sparse observations on deepwater cirri- 
 peds in which the naupliar stage is passed through in the 
 egg. Fully developed cyprid larvae or advanced 
 metanauplii are released at hatching. Barnard (1924) 
 found that over half (12 of 17) of South African Scal- 
 pellum species lack free-swimming naupliar stages; this 
 characteristic appears to be independent of adult depth 
 distributions. Complete naupliar development without 
 feeding (lecithotrophic development) is also known, 
 either with an irregular molt in nauplii and precocious 
 cyprid development (Anderson 1965) or with six naupliar 
 stages and cyprid (Kaufmann 1965). 
 
 DEFINITION AND DIAGNOSTIC 
 CHARACTERS 
 
 As described by Groom (1894), the basic anatomy of 
 the cirriped nauplius is well established (Kruger 1940; 
 Walley 1969). Walley (1969) extended Groom's observa- 
 tions on the internal anatomy of the nauplius (Semi- 
 
 balanus balanoides), but notable additions to the exter- 
 nal morphology of larvae will probably rest on scanning 
 electron microscopy (EM) studies, such as those recent- 
 ly reported by Walker (1973, 1974a) and Rainbow and 
 Walker (1976). 
 
 As a guideline to descriptions presented in this study, 
 a summary of external morphology and taxonomic 
 characters of cirriped larvae follows. Although in most 
 cases this represents a simple review of past literature, 
 some basic changes in terminology of larval structures 
 and setal types are proposed. 
 
 The dorsal surface of the nauplius (Fig. 1A, B) is com- 
 posed almost entirely of a unitary carapace shield 
 (Anderson 1973) or correctly, the cephalic shield (cs), 
 with a pair of prominent frontolateral horns (fh) an- 
 teriorly and a dorsal thoracic spine (DTS) posteriorly. 
 Ventrally, there are three pairs of jointed appendages: 
 the antennules (Anl), the antennae (An2), and the 
 mandibles (Mn). A pair of unjointed filiform appen- 
 dages — the frontal filaments — extend anteriorly between 
 the antennules. A prominent labrum (lb) lies between 
 the antennae and overhangs the mouth. The pos- 
 teroventral "postnaupliar region" (Anderson 1973) con- 
 sists of the abdominal process (AP) which terminates 
 with the furcal spines. The ventral surface between the 
 mouth and postnaupliar region has a complex array of 
 small processes referred to as the setose region. It in- 
 cludes the maxillary portion of the cephalon and the in- 
 cipient thorax. 
 
 Cephalic shield. Despite the virtually universal refer- 
 ence to the naupliar carapace in the literature, the 
 nauplius, by definition, lacks a true carapace (Anderson 
 1973; Moore and McCormick 1969; Newman pers. com- 
 mun.). In naupliar stages I-LQ the shield tapers directly 
 into the DTS. At stage IV, a distinct posterior shield (ps) 
 border is formed (see Fig. 5); this border usually has two 
 ps spines (see Fig. 4 IV- VI). The shield may also have 
 dorsal and/or lateral spines or lack spines entirely. 
 
 Frontolateral horns. These distinctive structures are 
 unique to cirriped nauplii, although their function re- 
 mains unknown (see Walker 1973). Their relative size or 
 orientation is often characteristic of the species or family. 
 Stage I nauplii have fh folded back along the carapace, 
 but beginning with stage II, the horns are extended in an 
 anterolateral direction. Willemoes-Suhm (1876) noted 
 fine setae extending from between the spined tips of fh in 
 Lepas larvae, however, using scanning EM, Walker 
 (1973) described shredded cuticle at the same location 
 for several balanomorph species. 
 
 Dorsal thoracic spine. Commonly called the "caudal 
 spine" this process originates dorsal to the thoracic an- 
 lage of the nauplius. Since the caudal furca of cirriped 
 nauplii, and of the cyprids, is homologous to the "caudal 
 spines" of copepod and other crustacean nauplii (Ander- 
 son 1973), the classical term is misleading. As suggested 
 by W. A. Newman, DTS has been adopted. Nearly al- 
 ways present and often barbed or serrate, the DTS is 
 greatly elongated in lepad species and least developed in 
 
h 
 
 s 
 
 r- 
 
 -1 
 
 Figure 1.— Descriptive terminology of barnacle larvae: ventral view (A) and lateral view (B) of Conopea galeata stage II nauplius; Chelonibia 
 patula cyprid (C) and detail of the antennule (D). abs, abdominal spines; An 1, antennule; An2, antenna; AP, abdominal process; ao, adhe- 
 sive organ (on the third segment of Anl); ce, compound eye; cf, caudal furca; cs, cephalic shield; ds, dorsal shield spine; DTS, dorsal thoracic 
 spine; en, endopodite; ex, exopodite, ff, frontal filament; fh, frontolateral horn; fs, furcal spines; gn, gnathobase; lb, labrum; Is, lateral shield 
 spines; me, median or naupliar eye; Mn, mandible; mr, maxillary region; oc, oil cells; pa, pigmented area; sr, setose region; ta, thoracic append- 
 age; tr, thoracic region. All scales = 0.1 mm. 
 
 chthamalid larvae. Its relative length compared with 
 shield and AP may provide diagnostic characteristics. 
 
 Frontal filaments. Recently studied by Kauri (1962, 
 1966), and Walker (1974a), their function remains de- 
 bated. Often closely folded to the body wall in stage I 
 nauplii, with the exception of some chthamalid species, 
 the fdaments are evident in all subsequent naupliar 
 stages. 
 
 Jointed appendages. The Anl is uniramous and con- 
 sists of four segments in late naupliar stages. The An2 is 
 
 biramous, the endopod and exopod arising from a two- 
 segmented base. By stage VI the exopod (= exopodite) 
 consists of nine segments and the endopod (= endopo- 
 dite) is three-segmented. Similar to the antenna, the Mn 
 is biramous with a two-segmented base, two-segmented 
 endopod, and five-segmented exopod. 
 
 Labrum. The lb is relatively large and rigidly fixed to 
 the body above the mouth. The shape of the free end ap- 
 pears to be a useful family characteristic. 
 
 Maxillary and thoracic regions. The setose region, pos- 
 terior to the true mouth and extending to the abdominal 
 
spines, is divided in two: the anterior maxillary and 
 posterior thoracic regions. Rudimentary maxillae and 
 anlage of the thoracic appendages will be evident in later 
 naupliar stages. Functional appendages first appear in 
 the cyprid. 
 
 Abdominal process. The AP arises from the ventro- 
 posterior body region and terminates in a stem bearing 
 spines of the caudal furca. Pairs of lateral abdominal 
 spines appear at stage II and increase in number with 
 subsequent molts. Norris and Crisp (1953) defined three 
 sets of serially homologous spines which develop in a 
 highly predictable order in balanid larvae (Fig. 4). 
 
 Setation. Setae are well developed on the limbs and 
 ventral body regions, serving both a natatory and feeding 
 function (Gauld 1959). The number and types of setae 
 are fundamental morphological characters which are, in 
 part, used for determining the naupliar stage (Fig. 4, 
 Table 4) and, to a lesser extent, the species. 
 
 Bassindale (1936) initiated use of a setation formula 
 similar to that used for copepod appendages. The formu- 
 la specifies only setal numbers and location. Jones and 
 Crisp (1954) devised a graphical method to show setal 
 numbers, types, and relative lengths. Newman (1965) 
 combined the simplicity of Bassindale's formula with the 
 informational content of the Jones and Crisp graphics to 
 create an alphabetical notation. Sandison (1967) further 
 modified Newman's system, adding additional setal 
 types and using numerical groupings of similar setae. For 
 a comparison of these setation formulae, see Figure 2. 
 
 The basic setation formula of Newman (1965) is used 
 in this study with some modifications. The initial four 
 setal types of cirriped larvae defined by Jones and Crisp 
 (1954) and Newman (1965) were expanded to seven types 
 by Sandison (1967) (Table 3). A similar but inde- 
 pendent trend to define specific setal types in decapod 
 larvae was initiated by Bookhout and Costlow (1974), 
 their setal types based on the definitions of crayfish setae 
 by Thomas (1970). Essentially two problems now exist: 
 1) additional setal types undefined by Sandison (1967) 
 have been observed in the present study, and 2) there are 
 two sets of terms used for respective cirriped and 
 decapod setal types. This latter situation does not seem 
 warranted based on comparative observations on deca- 
 pod larvae (Lang and Young 1977; Johns and Lang 1977). 
 
 B) 0.1.4-OA.3.4.3.G 
 
 C) I nil ■::: i-i s \f\ m g 
 ) P PPPP SSSS PSP sPCP PCP 
 
 E) P: 4P: — 4S: PSP: SP C C P. P C P:G 
 
 F) P: 4P — 4S: PSP SDCP.PCP:G 
 
 Figure 2. — Setation formulae for the mandible A) of stage IV Bal- 
 anus eburneus nauplius; B) formula of Bassindale (1936); C) for- 
 mula of Jones and Crisp (1954); D) formula of Newman (1965); E) 
 formula of Sandison (1967); F) formula used here (see also Table 3). 
 Scale = 0.1 mm. 
 
 Bookhout and Costlow (1974) organized the setal 
 terminology and descriptions of Thomas (1970) into sev- 
 en basic groups for describing the larvae of Portunus 
 spinicarpus. Four of these groups appear to apply equally 
 to cirriped larvae: 
 
 1. Simple setae are acuminate with no setules or pro- 
 jections. 
 
 2. Plumose setae possess fine hairlike setules coming 
 off opposite sides of the shaft. 
 
 3. Plumodenticulate setae bear hairlike setules on the 
 basal part of the shaft and fine or stout denticules 
 on the distal portion. 
 
 4. Cuspidate setae have enlarged bases and stout 
 shafts tapering to a point. These may be further 
 
 Table 3.— Setal types of cirriped nauplii. 
 
 Jones and Crisp (1954) 
 Symbol-Type 
 
 Newman (1965) 
 Symbol-Type 
 
 Sandison (1967) 
 Symbol-Type 
 
 Present 
 Symbol-Type 
 
 : . without setules 
 | with setules 
 
 £ comb-like 
 
 G - gnathobase 
 [ simple or plumose 
 
 S - simple 
 P - plumose 
 
 C - combed 
 
 G - gnathobase 
 S' - S, sometimes P 
 P' - P, sometimes S 
 
 S - simple 
 
 P - plumose 
 
 F - feathered 
 
 P c - setose, serrate tip 
 
 C - combed 
 
 H - hispid 
 
 G - gnathobase 
 
 S' - S, sometimes P 
 
 P' - P, sometimes S 
 
 S - simple 
 
 P - plumose 
 
 F - feathered 
 
 D - plumodenticulate 
 
 B - bristled 
 
 C - cuspidate 
 
 H - hispid 
 
 G - gnathobase 
 
 S p - S, sometimes P 
 
 P s - P, sometimes S 
 
 P u - P, sometimes D 
 
Figure 3.— Examples of barnacle larvae setal types: A) simple; B-E) plumose; F) feathered; G) plumoden- 
 ticulate; H-K) cuspidate; L) hispid; M) bristled; N, P) gnathobases. Scale = 0.1 mm. 
 
 specified as denticulate, cuspidate, or plumo- 
 denticulate cuspidate types. 
 
 Incorporation of these groups, setal types described by 
 Sandison (1967), and present observations, result in the 
 following setal types used in this paper: 
 
 Simple (S): setae with no setules or projections (Fig. 
 3A). 
 
 Plumose (P): setae with fine hairlike setules, short or 
 long, usually but not always coming off opposite 
 sides of the shaft (Fig. 3B, C, D, E). 
 
 Feathered (F): plumose setae with dense "downy" 
 setules and flattened spatulate shaft (Fig. 3F). 
 
 Plumodenticulate (D): plumose setae with denticu- 
 late or serrate tip (Fig. 3G). 
 
 Cuspidate (C): setae with enlarged base and stout 
 shaft tapering to a point. The presence of stout to 
 fine denticules, often comblike in orientation, is 
 typical (Fig. 3H, I, J, K). 
 
 Hispid (H): cuspidate setae with flattened modified 
 shaft (Fig. 3D. 
 
 Bristled (B): plumose setae with basal portions of 
 shaft serrate or "bristled" (Fig. 3M). 
 
 The gnathobase (G) is classically defined as a rigid 
 toothed or "biting" process and is located on the basal 
 segment of both An2 and Mn in cirriped larvae. Rain- 
 bow and Walker (1976) also refer to the An2 endopod 
 cuspidate seta (Fig. 3K) as a G. It should be noted that 
 the An2 G is a unique structure (Fig. 3N) while the Mn G 
 (Fig. 3P) differs little from other cuspidate setae. By 
 convention, any rigid process on the basal segment of the 
 appendages will be considered a G; setae at other loca- 
 tions will be classified as one of the above listed types. 
 
 Semantics and definitions of setal types have been 
 somewhat altered from those listed by Sandison, but 
 only one symbol has been changed (P° = D), thus 
 eliminating the superscript and repeated use of P. Fea- 
 thered setae described by Sandison (Fig. 3E) for 
 chthamalid larvae, often closely resemble postaxial plu- 
 mose setae (An2, endopod) of some balanid larvae, but 
 feathered setae have a distinct "spatulate shaft"; and 
 enlarged flattened basal region is obvious. Similarly, the 
 
"bristled" proximal shafts of some Anl setae of Octo- 
 lasmis and Lepas larvae are quite distinctive; a new setal 
 type (bristled) has been introduced. 
 
 Superscripts will be used to designate setal type varia- 
 bility. Thus, P s infers plumose seta, sometimes simple; 
 S 1 ', simple seta, sometimes plumose; P D , plumose seta, 
 sometimes plumodenticulate; etc. 
 
 The cyprid larva (Fig. 1C) is enclosed by a bivalved 
 carapace. The carapace may appear textured or sculp- 
 tured in some species, but is relatively smooth in all 
 Carolina species examined. Using scanning EM, nu- 
 merous small sensory setae and the fh pores are evident 
 on the carapace surface (Walker and Lee 1976). 
 
 The naupliar An2 and Mn are transient structures in 
 the cyprid and are reduced to rudimentary groups of cells 
 during the metamorphosis from nauplius to cyprid (Wal- 
 ley 1969). The Anl, however, is retained as the primary 
 sensory and attachment structure. Antennule setation is 
 greatly reduced and a prominent attachment organ is 
 present (Fig. ID). Nott and Foster (1969) studied the 
 Anl of Semibalanus balanoides cyprids in detail and 
 concluded that attachment probably occurs by an adhe- 
 sive disc. At the level of light microscopy, the Anl shows 
 little variation between different species. 
 
 Propulsion is provided by six pairs of biramous thora- 
 cic swimming appendages. Their embryonic develop- 
 ment is clearly evident in the basal region of the AP in 
 stage VI nauplii. The articulate rami of the furca has 
 complex sensory processes and perhaps aids in contour 
 assessment (Walker and Lee 1976). 
 
 The internal anatomy of the cyprid has been reviewed 
 and studied by Walley (1969). Structures readily evi- 
 dent in examination of whole specimens include: the 
 naupliar eyespot, paired compound eyes, various pig- 
 mented areas, and oil cells. 
 
 LARVAL DESCRIPTIONS 
 
 All cirriped species studied at North Inlet exhibit the 
 typical larval development of six planktotrophic 
 naupliar and cyprid stages. The newly hatched stage I 
 nauplius is nonfeeding and capable of only weak swim- 
 ming activity. This stage rapidly molts to planktotrophic 
 stage II; it is rarely encountered in plankton tows. The 
 remaining five naupliar stages and cypris comprise the 
 normal planktonic component of the cirriped life cycle 
 and will be the main concern of the following descrip- 
 tions and key. 
 
 With each molt the nauplius increases in size and com- 
 plexity. All known planktotrophic balanomorph nauplii 
 exhibit basic morphological changes at each molt which 
 allows the accurate staging of any species. A diagram- 
 matic outline of key morphological features is presented 
 in Figure 4; these features will be considered the "nor- 
 mal" developmental sequence. Of North Inlet species, 
 only Octolasmis larvae differs significantly from this pat- 
 tern (Lang 1976). 
 
 Setation of the naupliar appendages is also quite uni- 
 form among most balanid species. Based on a review of 
 existing descriptions (Table 2), the "normal" or ex- 
 
 pected setal counts are indicated in Table 4. Setal counts 
 between different species vary little in most instances; 
 variations in setal types occur more often. Although 
 detailed studies of setae serve little practical use in rou- 
 tine staging or identification of larvae, details of seta- 
 tion may provide useful information for studies concern- 
 ing taxonomy, regional variations, feeding mechanisms, 
 etc., and should not be ignored in initial larval descrip- 
 tions. 
 
 Balanus venustus Darwin 
 
 Darwin's (1854) variety B. amphitrite amphitrite was 
 raised to specific rank by Harding (1962). Henry and 
 McLaughlin (1975) considered Darwin's varieties B. a. 
 niveus, B. a. modestus, and B. a. obscurus as synony- 
 mous with B. venustus. Although confusion exists in the 
 early literature (see Zullo 1966), B. venustus is a pre- 
 dominant shallow-water subtidal species from New En- 
 gland to Florida. 
 
 All specimens collected in North Inlet (Georgetown, 
 S.C.) were found in subtidal habitats. Balanus venustus 
 was the predominant species on all subtidal debris: 
 wood, metal, plastic, glass, shells (but not oyster beds). 
 It was abundant on hermit crab shells and occasionally 
 on the carapace of horseshoe crabs; spider crabs, Libinia 
 emarginata; and blue crabs. 
 
 Although B. venustus is a common species, no de- 
 scriptions of its larvae seem to exist. Numerous hatches 
 of larvae were successfully reared; adults used to obtain 
 larvae for the following descriptions were positively iden- 
 tified by Dora Henry. 
 
 Stage I. (Fig. 5A). Typical stage I nauplius with rudi- 
 mentary AP and DTS; fh folded rearward, but rarely col- 
 lapsed completely against body. 
 
 Stage II. (Fig. 5B). Frontolateral horns extended near- 
 ly perpendicular to median body axis; anterior shield 
 (as) margin slightly convex to flat; DTS and AP well 
 developed, distinctly barbed. Spination quite distinct; 
 anterior margin of shield with four small lateral spines, 
 side margins with four pairs of similar spines, and one 
 larger spine pair at future location of ps margin; one 
 short median dorsal spine also present. Entire shield 
 margin spinulose (numerous minute spines present). 
 
 Stage III. (Fig. 5C). Frontolateral horns directed 
 slightly forward; as margin slightly arched with two 
 small lateral spines, spinulose margins, and closely 
 spaced pair of median dorsal spines. Maxillules repre- 
 sented by one stout simple seta (see Fig. 8B). 
 
 Stage IV. (Fig. 5D). Shield marginal spination further 
 reduced to a variable number of small lateral spines and 
 spinulation; paired dorsal spines similar to stage III. Pos- 
 terior shield margin present; ps spines straight, rela- 
 tively stout. The DTS is long, generously barbed; AP 
 with series two spine pair and single well-developed me- 
 dian spine (see Fig. 8C). 
 
 Stage V. (Fig. 5E). Very similar to stage IV. Shield 
 margin spinulose, no larger lateral spines present; paired 
 dorsal spines widely spaced and minute. Series three 
 
one preaxial 
 seta 
 
 split tip 
 
 two preaxial 
 setae 
 
 6pr. series 
 two spines 
 
 1pr. each series 
 two & three spines 
 
 Figure 4. — Diagnostic morphological features of balanomorph nauplii at each stage. Abdominal spine designations are adapted from Norris 
 
 and Crisp (1953) and Moyse (1961). 
 
 Table 4. — Typical setation counts for balanid nauplii. 
 
 Stage 
 
 Antennule 
 
 Antenna 
 
 Mandible 
 
 I 
 
 0.4.2.1.1 
 
 0.1.4-0.3.2.2.2.G 
 
 0.1.3-0.3.2. 2. 2. G 
 
 II 
 
 0.4.2.1.1 
 
 0.2.5-0.3.2.2.3.G 
 
 0.1.4-0.3.2.3.2.G 
 
 m 
 
 1.4.2.1.1 
 
 0.2.5-0.3.2.2.4.G 
 
 0.1.4-0.3.3.3.3.G 
 
 IV 
 
 1.1.4.2.1.1 
 
 0.3.6-0.5.3.2.4.G 
 
 0.1.4-0.4.3.4.3.G 
 
 V 
 
 1.1.1.4.2.1.1.1 
 
 ( )- 1 0.5.3.2.4. G 
 
 0.1.5-0.4.4.4.3. G 
 
 VI 
 
 1.1.1.4.2.1.2.1 
 
 ( )? 0.5.3.2.4. G 
 
 0.1.5-0.4.4.4.3. G 
 
 ■Variable configuration with a total of 10 or 11 setae. 
 ; Variable configuration with a total of 11 or 12 setae. 
 
 spine pair present on AP; series two pair and median 
 spine as in stage IV (see Fig. 8E, F). 
 
 Stage VI. (Fig. 5F). Spinulation of shield margin often 
 indistinct; most evident on anterior and posterior mar- 
 gins. The ps spines reduced in length but stout; DTS 
 long and well armed. 
 
 Cyprid. Virtually identical to B. improuisus (Jones 
 and Crisp 1954). No apparent distinctive characteris- 
 tics. 
 
 Characteristic morphological features associated with 
 each balanid naupliar stage (Fig. 4) are closely followed 
 in the larval development of B. venustus. Lateral shield 
 spination is somewhat variable; in some hatches the 
 lateral shield spines are less distinct and generally smal- 
 ler. 
 
 Setation of the naupliar stages (Table 5) closely fol- 
 lows the normal balanid pattern (Table 4). The first 
 preaxial seta of Anl is plumose at stage III (Fig. 6C), as 
 
Figure 5.- 
 
 -Balanus venustus. Shield outlines of stages I-VI (A-F) and cyprid carapace profile (G). Scales 
 
 = 0.1 mm. 
 
 Table 5. — Setation formulae for nauplii of Balanus venustus. 
 
 Stage 
 
 Anl 
 
 An2 
 
 Mn 
 
 VI SPPPSPPSPPPSS 3P8P PPSPP PSP PD PCP G P5P 4S DSPS D SCP PCP G 
 
 V 
 
 S P P PSPP SP S P 
 
 s 
 
 3P6PS 
 
 PPSPP PSP PD PCP G 
 
 P4PS 
 
 IV 
 
 S P PSPP SP P 
 
 s 
 
 2P6PS 
 
 PPSPS PSP PD PCP G 
 
 P4P 
 
 III 
 
 P PSPP SP P 
 
 s 
 
 2P5P 
 
 PP P P S PD PCS G 
 
 P3PS 
 
 II 
 
 SSPS SP P 
 
 s 
 
 SP4PS 
 
 PP S P SPDPC G 
 
 P3PS 
 
 I 
 
 SSSS SS s 
 
 s 
 
 S4S 
 
 SS S S S SS SS G 
 
 S3S 
 
 4SDSPSD SCP PCP G 
 4S D SS P°SCP PCP G 
 3SP SSP° CPPCPG 
 3SP S P CSPC G 
 
 3SS S S S SS G 
 
 opposed to a simple seta in many species. The first post- 
 axial setal group of the Mn endopod has one to two plu- 
 modenticulate setae beginning with stage III (Fig. 61, J). 
 The An2 exopodal setae are relatively stout; the endo- 
 pod is well developed, with one less seta than expected 
 (stages III-VI) in the last postaxial setal group adjacent 
 to the G (Fig. 7). 
 
 The DTS remains notably long in late stage nauplii 
 and is distinctly barbed in all stages (II- VI). The AP is 
 also well developed but remains shorter than the DTS; 
 abdominal spines are stout and easily observed (Fig. 8A- 
 G). Maxillule setation first appears at stage III and in- 
 creases to six (5 long, 1 short) stout simple setae by stage 
 VI. 
 
 The lb is trilobed, the median lobe even with or slight- 
 
 ly extending beyond the lateral lobes (Fig. 8H-J). Fine 
 teeth or denticulations may be present along the lateral 
 lobe margins. Three teeth are often present on the mar- 
 gin of the median lobe. 
 
 Larvae increase in size at each molt; size variability in- 
 creases in later stages (Table 15). Under similar rearing 
 conditions the mean size of B. venustus nauplii is dis- 
 tinctly larger than B. eburneus and B. amphitrite. Of 
 North Inlet balanids examined, only Chelonibia patula 
 and Conopea galeata larvae are consistently larger 
 (Table 15); B. trigonus have similar sized larvae. 
 
 Balanus eburneus Gould 
 
 Balanus eburneus ranges from New England to Brazil 
 in the western Atlantic and occurs from low water to 37 
 
Figure S.-Balanus venustus. Naupliar antennule of stage I (A), II (B), III (C), IV (D), V (E), VI (F); naupliar mandible of stage II (G), III (H), 
 
 IV (I), VI (J). Scale = 0.1 mm. 
 
 10 
 
Figure l.—Balanus venustus. Naupliar antenna of stage I (A), II (B), III (C), IV (D), V (E), VI (F). Scale = 0.1 mm. 
 
 11 
 
Figure S.—Balanus venustus. Abdominal process of stage II (A), III (B), IV (C), V (E, F), VI (G); labrum of stage I (H), II 
 
 (I), IV (J). Scales = 0.1 mm. 
 
 m (Henry and McLaughlin 1975). McDougall (1943) 
 noted it is the most abundant intertidal barnacle at 
 Beaufort, N.C. At North Inlet, B. eburneus is predomi- 
 nant on all intertidal wood structures from about mid- 
 tide level and below. It rapidly fouls wood and plastic 
 boat surfaces and is common on both intertidal and sub- 
 tidal oysters. Intertidal specimens tend to be crowded 
 and cylindrical in form while subtidal specimens, far less 
 abundant, are conical. 
 
 The larvae of B. eburneus have been reared and de- 
 scribed by Costlow and Bookhout (1957) using eggs from 
 adults collected at Beaufort. Larvae were also reared, but 
 not described, by Freiberger and Cologer (1966) using 
 adults collected at Miami, Fla. 
 
 Numerous cultures of B. eburneus have been reared at 
 South Carolina for this study and for work by Jorgensen 
 (1976). Larval morphology closely matches results re- 
 
 ported by Costlow and Bookhout (1957) in major fea- 
 tures; however, numerous discrepancies in setation were 
 noted. 
 
 The shield of B. eburneus nauplii is plain in all stages, 
 lacking dorsal or lateral shield spines. Morphological 
 changes at each molt follow the normal pattern (Fig. 4). 
 The fh are moderate in length and, beginning with stage 
 II, are directed forward. The as margin is arched; the 
 shield outline is smoothly elliptical (Fig. 9). 
 
 Setal formulae for all stages (Table 6) follow the usual 
 balanid pattern (Table 4). Based on present observa- 
 tions of four separate hatches, stage II setation de- 
 scribed by Costlow and Bookhout (1957) does not appear 
 typical. Plumodenticulate setae are present on the Mn 
 endopods (stages IV- VI); up to four plumodenticulate 
 setae may be present at stage VI. 
 
 12 
 
Figure 9. — Balanus eburneus. Shield outlines of stages II-VI (A-E); abdominal process of stage II (a), IV (c), 
 
 V (d), VI (e). Scale = 0.1 mm. 
 
 Table 6. — Setation formulae for nauplii of Balanus eburneus. 
 
 Stage 
 
 Anl 
 
 An2 
 
 Mn 
 
 VI SPPPSPPSPPPSS 4P8P 
 
 V SPPPSPPSPSP S 3P7PS 
 
 IV SPPSPPSP P S 2P6PP S 
 
 HI SPSPPSP P S 2P5P 
 
 n sspssp p s SP4PS 
 
 PPSPP PSP PD PSCP G P4PP 
 PPSPP PSP PD PSCP G P4PS 
 PPSP* PSP PD PSCP G P4P 
 PP P PS PDPSCSG P3PS 
 PP S PS PDP CSG P3PS 
 
 4S SDSD DSCD 1 PCP G 
 4SSDSDDSCD'PCPG 
 4S DSPDSCD P PCPG 
 3S PSS D CP PCPG 
 3S PS P CS PC G 
 
 The DTS is distinctly longer than the AP in all stages 
 (Fig. 9a-e). Abdominal spination is typical (Fig. 4); one 
 median spine is present in stages IV and V. 
 
 The lb is trilobed with a distinctly longer median lobe. 
 Although the median lobe margin may have minor den- 
 ticulation, no distinct teeth are present. 
 
 Balanus eburneus nauplii are generally small, averag- 
 ing slightly larger than B. a. amphitrite larvae (Table 
 15). Size ranges of larvae reared at 25°C are similar to 
 those reported by Costlow and Bookhout (1957) except 
 for width. 
 
 Balanus amphitrite amphitrite Darwin 
 
 Balanus amphitrite amphitrite is a cosmopolitan spe- 
 cies of warm and temperate seas. It is usually intertidal, 
 often in brackish water. On the eastern coast of the 
 United States, B. amphitrite is common from Florida 
 
 north to the Carolinas and has been reported as far north 
 as Massachusetts (Zullo 1963). At North Inlet, it is a 
 common intertidal species, generally situated between 
 upper intertidal Chthyamalus fragilis and lower inter- 
 tidal B. eburneus on wood pilings. 
 
 The complex and often confused status of B. a. 
 amphitrite has been reviewed by Henry and McLaugh- 
 lin (1975). Of particular significance for a review of exist- 
 ing literature is the placement of B. a. communis, B. a. 
 denticulata, and B. a. hawaiiensis in synonymy with B. 
 a. amphitrite. 
 
 Costlow and Bookhout (1958) described larvae reared 
 from North Carolina adults. Larvae have also been de- 
 scribed from Japan (Hudinaga and Kasahara 1942), Bra- 
 zil (Lacombe and Monteiro 1972), and India (Pillai 1958; 
 Karande 1973). Balanus a. amphitrite larvae obtained 
 from numerous diet and temperature studies have been 
 compared with these existing descriptions. 
 
 13 
 
Figure 10. — Balanus amphitrite amphitrite. Shield outlines of naupliar stages I-VI (A-F); cyprid carapace 
 profile (G); abdominal process of stage II (a), IV (d), VI (f). Scales = 0.1 mm. 
 
 Balanus amphitrite nauplii lack dorsal or lateral shield 
 spines, except for stage II. Stage II nauplii may have a 
 pair of small blunt spines on the lateral shield margin 
 (Fig. 10B). Morphological changes at each molt are typi- 
 cal (Fig. 4). At stage II, the fh extend nearly perpendicu- 
 lar to the shield midline; the fh tips often bend slightly 
 rearward. This configuration remains consistent in later 
 stages (Fig. 10). 
 
 Setation is typical (see Table 8). The An2 exopod setae 
 of stage VI nauplii are variable (IIP, UPS, 12P). Man- 
 dibular plumodenticulate setae are not well developed 
 and only one such seta occurs consistently. 
 
 The DTS is longer than the AP in all stages (Fig. 10a, 
 d, f). Abdominal spination is typical; one median spine is 
 present in stages IV and V. 
 
 The lb is trilobed; the median lobe normally extends 
 slightly beyond the lateral lobes. All lobes have nu- 
 merous simple setae, but no teeth are present. 
 
 Balanus amphitrite larvae are small (Table 7), gen- 
 erally intermediate in size between Chthamalus fragilis 
 and B. eburneus (Table 15). The rearward orientation of 
 the fh is the most useful character for recognition of later 
 stage nauplii. Stage II nauplii are readily confused with 
 those of B. improvisus; care must be taken to note the 
 small lateral spines and lack of distinct labral teeth for 
 B. amphitrite larvae. Cyprids are very similar to those of 
 other amphitrite -complex species; no means to identify 
 this stage to species has been devised. 
 
 Present observations vary in numerous aspects from 
 existing descriptions of B. amphitrite larvae. The size of 
 larvae reported by all investigators (Table 7) is in general 
 agreement, with two exceptions: the widths of all 
 
 stages are consistently greater in the study of Costlow 
 and Bookhout (1958) and the later stage (IV-VI) larvae 
 reported by Pillai (1958) are relatively small and show 
 little increase per molt. Interestingly, Pillai's work repre- 
 sents the only study using planktonic material; the smal- 
 ler sizes could represent a real phenomenon, but ob- 
 servational error is more likely using planktonic 
 material. 
 
 Setation of larvae does not completely agree in any 
 study. It unfortunately is conjecture as to what degree 
 this represents observational error in descriptions or real 
 variation in the larvae. With the exception of the stage 
 III Mn exopod, present setal counts agree with those of 
 Costlow and Bookhout (1958). The descriptions of 
 Hudinaga and Kasahara (1942) and Pillai (1958) are suf- 
 ficient to allow generation of comparative setal formulae 
 (Table 8). As indicated in the table, only three minor 
 points of difference exist between the Japanese descrip- 
 tion and the present study. However, in the study by Pil- 
 lai, stages V and VI setation shows significant variation. 
 This sheds further doubt on the accuracy of his plankton 
 identification. 
 
 Karande (1973) reports no median spine on the AP of 
 stages IV and V. Hudinaga and Kasahara (1942) and 
 Costlow and Bookhout (1958) make no mention of one, 
 however, in agreement with present observations; Pillai 
 (1958) reports a single median spine for both stages. 
 
 Balanus improvisus Darwin 
 
 Balanus improvisus occurs along the entire Atlantic 
 coast of the United States and is found from the inter- 
 tidal zone to 46 m (Henry and McLaughlin 1975). The 
 
 14 
 
Table 7. — Size of Balanus eburneus (top) and Balanus 
 amphitrite (bottom) larvae reported from various 
 sources: Costlow and Bookhout (1957) (BB); Costlow 
 and Bookhout (1958) (CC); Hudinaga and Kasahara 
 (1942) (HK); Karande (1973) (K); Lacombe and Mon- 
 teiro (1972) (LM); Pillai (1958) (P); Sandison (1954) 
 (S); and present results (PR). Total length (TL), shield 
 length (SL), and width (W) in millimeters. 
 
 Stage 
 
 Source 
 
 TL 
 
 SL 
 
 W 
 
 n 
 
 BB 
 
 0.32-0.34 
 
 
 0.21-0.23 
 
 
 PR 
 
 0.32-0.36 
 
 
 0.16-0.18 
 
 m 
 
 BB 
 
 0.35-0.38 
 
 
 0.23-0.27 
 
 
 PR 
 
 0.36-0.41 
 
 
 0.18-0.23 
 
 IV 
 
 BB 
 
 0.40-0.42 
 
 0.30-0.33 
 
 0.27-0.32 
 
 
 PR 
 
 0.42-0.45 
 
 0.30-0.33 
 
 0.23-0.25 
 
 V 
 
 BB 
 
 0.44-0.48 
 
 0.35-0.38 
 
 0.29-0.34 
 
 
 PR 
 
 0.46-0.57 
 
 0.33-0.44 
 
 0.26-0.32 
 
 VI 
 
 BB 
 
 0.54-0.60 
 
 0.42-0.50 
 
 0.36-0.39 
 
 
 PR 
 
 0.57-0.62 
 
 0.39-0.46 
 
 0.32-0.37 
 
 II 
 
 CC 
 
 0.25-0.30 
 
 
 0.19-0.24 
 
 
 HK 
 
 0.26 
 
 
 0.16 
 
 
 K 
 
 0.30 
 
 
 
 
 LM 
 
 0.31 
 
 
 0.15 
 
 
 P 
 
 0.29 
 
 
 0.16 
 
 
 S 
 
 0.32 
 
 
 0.16 
 
 
 PR 
 
 0.28-0.34 
 
 
 0.12-0.16 
 
 in 
 
 CC 
 
 0.30-0.34 
 
 
 0.22-0.27 
 
 
 HK 
 
 0.30 
 
 
 0.19 
 
 
 LM 
 
 0.38 
 
 
 0.17 
 
 
 P 
 
 0.36 
 
 
 0.19 
 
 
 PR 
 
 0.31-0.36 
 
 
 0.16-0.20 
 
 IV 
 
 CC 
 
 0.35-0.39 
 
 0.25-0.32 
 
 0.25-0.32 
 
 
 PR 
 
 0.33-0.40 
 
 0.24-0.30 
 
 0.17-0.23 
 
 V 
 
 CC 
 
 0.41-0.47 
 
 0.30-0.35 
 
 0.25-0.32 
 
 
 PR 
 
 0.40-0.47 
 
 0.28-0.35 
 
 0.24-0.28 
 
 
 P 
 
 
 0.27 
 
 0.27 
 
 VI 
 
 CC 
 
 0.47-0.53 
 
 0.35-0.40 
 
 0.35-0.43 
 
 
 PR 
 
 0.47-0.57 
 
 0.34-0.39 
 
 0.27-0.32 
 
 
 P 
 
 
 0.29 
 
 0.27 
 
 Figure 11. — Balanus improvisus. Shield outlines of naupliar stages 
 II-VI (A-E). Scale = 0.1 mm. 
 
 species can withstand low salinities, is predominant in 
 brackish water, and is often associated with B. subal- 
 bidus or, in Europe Eliminius modestus (Jones and 
 Crisp 1954). In North Inlet, B. improvisus was conspicu- 
 ously absent in the major tidal creeks with salinities 
 generally above 20°L but was common in waterways 
 draining abandoned ricefields and also upper Winyah 
 Bay, usually attached to concrete, bricks, or debris. 
 
 Table 8. — Setation formulae for nauplii of Balanus a. amphitrite as reported in different studies. 
 Complete formulae for the present study (Pr) are given; differences from these formulae as derived 
 from descriptions by Hudinaga and Kasahara (1942) (HK) and Pillai (1958) (PL) are noted. 
 
 Stage Study 
 
 Anl 
 
 An2 
 
 Mn 
 
 Pr S S P PSPP SP PPS S 3P 9P PPSPP PSS PD PSCP G 
 VI HK 
 
 PL 3P7PSPP PP 
 
 Pr SSPPSPPSPSPS 3P7PSPPSP P PSS PD PSCP G 
 V HK PPSPP PPS 
 
 PL SPPSPPSP PS 2P6PSPP PP PPSPDPPCPG 
 
 P4PS'' 4S PSPS DSCP PCP G 
 
 P4PS 
 
 P4PS 4S PSPS DSCP PCP G 
 
 P5P 
 
 Pr SPPSPPSP PS 3P5PSPPSPS PSS PD PSCP G 
 
 IV HK SSPSPPSP PS PPSPP 
 
 PL 2P6PSPP PS PPCP 
 
 P3PS P 4SPSP DSCP PCP G 
 
 PPS 
 P4P 
 
 Pr SPSPPSP PS 2P5P PP P PS PDPSCPG 
 
 III HK SSSPSSP PS PP S 
 
 PL PP P P CP 
 
 P3PS 3SPSS D CPPCPG 
 4SPPS 
 PSS 
 
 Pr 
 
 SSPSSP PS SP4PSPPS PS PDP CSG P3PS 3S PS P CS PC G 
 
 15 
 
Figure 12.— Balanus improvisus. Antenna of stage IV (A); antennule of stage IV (B); labrum of stages II and IV (C); abdominal 
 
 process of stage II (D), IV (E), V (F), VI (G). Scale = 0.1 mm. 
 
 Balanus improvisus larvae were reared both from 
 North Inlet and Rhode Island adults (Pettaquamscutt 
 Pond) and compared with the excellent descriptions of 
 planktonic larvae from the United Kingdom and Baltic 
 regions (Jones and Crisp 1954). 
 
 The shield of B. improvisus nauplii (Fig. 11) is with- 
 out lateral or dorsal spines in all stages. Morphological 
 development at each stage follows the expected sequence 
 (Fig. 4); ps spines are present in stages IV- VI. The fh of 
 stage II nauplii may extend nearly perpendicular to the 
 carapace midline, much as in B. amphitrite, but more of- 
 ten are directed slightly forward. In stage III larvae, the 
 fh base extends at a slight forward angle, however, the 
 top curves back. Frontolateral horns in stages IV- VI ex- 
 tend slightly forward similar to B. eburneus larvae. 
 
 Setation follows a normal pattern: the setal formula 
 is nearly identical to that of B. eburneus (Table 6). Stage 
 IV nauplii have five An2 endopod terminal setae (Fig. 
 12 A), as opposed to four setae in B. eburneus. As noted 
 by Jones and Crisp (1954), the Mn endopod is relatively 
 large (Fig. 12B); the Mn G is well developed. Up to four 
 Mn plumodenticulate setae are present in stages IV-VI. 
 
 The AP spination is typical (Fig. 12D-G). One pair of 
 lateral series two spines and a small median spine are 
 present in stages IV and V. The furcal stem is long; the 
 AP and DTS are nearly equal in length in stage IV (Fig. 
 12E) but the AP is usually longer in stages V and VI (Fig. 
 12F, G). 
 
 The lb (Fig. 12C) is trilobed; the median lobe extends 
 beyond the lateral lobes. In South Carolina nauplii, the 
 
 16 
 
median lobe has a distinct pair of lateral teeth; two-four 
 smaller median teeth are also present in earlier naupliar 
 stages. These teeth are less developed in Rhode Island 
 nauplii and are easily overlooked; they are not described 
 for European material (Jones and Crisp 1954). 
 
 The larvae of B. eburneus and B. improvisus are very 
 similar both in size and morphology. Stage II nauplii of 
 these species are nearly the same size in South Carolina 
 during the summer; however, Rhode Island nauplii and 
 winter South Carolina stage II nauplii are noticeably 
 larger (see Table 15). Later stages of B. improvisus tend 
 to be larger but size ranges overlap. In stages II and III, 
 the fh of B. improvisus, particularly the larger cool-wa- 
 ter forms, tend to extend perpendicular to the shield; the 
 fh of B. eburneus always extend distinctly forward. 
 Balanus improvisus nauplii have distinct teeth on the 
 median labral lobe, this in contrast to B. eburneus and 
 B. amphitrite. In stages IV and VI, B. improvisus nauplii 
 have a broad more rounded cs relative to B. improvisus 
 and B. eburneus, the median AP spine is small or ab- 
 sent, and the AP and DTS are about equal in length. The 
 cyprid of B. improvisus is quite similar in shape to other 
 species of the B. amphitrite complex. Although often the 
 largest sized cyprid in this species complex (Table 16), 
 size ranges overlap and no means for positive identifica- 
 tion is presently available. 
 
 Balanus subalbidus Henry 
 
 A recently described species (Henry 1973), B. subalbi- 
 dus ranges from Massachusetts to Florida on the At- 
 lantic coast (Henry and McLaughlin 1975). It is nor- 
 mally found in intertidal brackish water habitats. No 
 specimens were found in North Inlet, but numerous in- 
 dividuals were collected from intertidal debris at Winyah 
 
 Bay sites. Identification of samples was provided by Dora 
 Henry. 
 
 Larvae of B. subalbidus have not been previously 
 reared or described. The following descriptions are based 
 on a small number of larvae successfully reared to stage 
 VI nauplii. The cyprid stage was not obtained nor were 
 additional hatches obtained to verify results. 
 
 Balanus subalbidus are generally small and narrow. 
 Early stages average about the same size as B. amphi- 
 trite nauplii, but late stages approach or surpass sizes 
 observed for B. eburneus larvae reared under similar 
 conditions (Table 15). 
 
 In general appearance, but not size, B. subalbidus 
 nauplii resemble those of Semibalanus balanoides. The 
 carapace is long and narrow with very short, straight fh 
 (Fig. 13). No lateral or dorsal shield spines are present. 
 The ventral shield spines (stages IV- VI) are long, deli- 
 cate, and often curved outward. 
 
 Setation is virtually identical to that observed for B. 
 amphitrite (Table 8). Only the An2 of stage IV varies 
 from B. amphitrite; nine plumose setae are on the exo- 
 pod, but only two postaxial setae are present on the 
 terminal endopod segment (3P:6P-PPSPS:PS:PD: 
 PSCP:G). 
 
 The trilobed lb has a distinctly longer median lobe in 
 all stages (Fig. 13F). No teeth or spines were observed. 
 
 The AP is relatively small; the furcal stem is excep- 
 tionally short, the maximum observed length being indi- 
 cated in Figure 13G. In all stages the DTS is distinctly 
 longer than the AP. Abdominal spination is typical; one 
 lateral pair of series two spines but no median spines are 
 present in stages IV and V. 
 
 The narrow shield and short fh readily distinguish B. 
 subalbidus from all South Carolina species except per- 
 haps B. amphitrite. Care must be taken to note the long- 
 
 Figure 13. — Balanus subalbidus. Shield outlines of 
 naupliar stages II-VI (A-E); labrum of stage IV (F); 
 abdominal process of stage IV (G). Scale = 0.1 mm. 
 
er fh and broader shield of stages II and III of B. 
 amphitrite nauplii. Stages IV-VI are readily distin- 
 guished on the basis of long ps spines and very short AP 
 of B. subalbidus nauplii. 
 
 Balanus trigonus Darwin 
 
 Balanus trigonus is a warm-water cosmopolitan spe- 
 cies which has been reported as far north as North Caro- 
 lina (Ross et al. 1964). It is subtidal, frequently associ- 
 ated with B. venustus and B. calidus, and has been 
 reported on numerous hard substrates, including shells, 
 crabs, and sponges (Werner 1967). In North Inlet, B. 
 trigonus was found on hermit crab shells, usually single 
 individuals associated with B. venustus. 
 
 Sandison (1954) briefly described B. trigonus nauplii 
 from South African plankton samples. Freiberger and 
 
 Cologer (1966) reared larvae from Miami, and Barker 
 (1976) reared and described larvae from New Zealand. 
 Present results are based on larvae reared at 25 °C from 
 a single hatch released from a North Inlet adult. 
 
 Balanus trigonus nauplii lack dorsal or lateral shield 
 spines in all stages (Fig. 14). Morphological changes at 
 each molt are consistent with the expected pattern (Fig. 
 4). At stage II, the fh are directed slightly rearward; in 
 subsequent stages the fh extend anteriorly. The shield of 
 stages IV-VI is broad with a moderately arched dorsal 
 surface; the paired ps spines are well-developed. The 
 cyprid is large (see Table 16) with a distinct carapace 
 profile relative to other Carolina species (Fig. 36). The 
 anterior carapace region is wide and well-rounded; a 
 somewhat "teardrop" shape results. 
 
 Setation (Table 9) follows the typical balanid pattern 
 although some minor variations were noted. Denticulate 
 
 Figure 14. — Balanus trigonus. Shield outlines of nau- 
 pliar stages II-VI (A-E). Scale = 0.1 mm. 
 
 Table 9.— Setation formulae for nauplii of Balanus trigonus. 
 
 Stage 
 
 Anl 
 
 An2 
 
 Mn 
 
 VI SPPPSPPSPPPSS 3P8P 3PSP PSP PD SPCP G P5P 3SD SDSD DSCP PCP G 
 
 V SSPPSPPSPSP S 3P 7PS 3PSP PSP PD SPCP G P 4PS 3SD SDSD DSCP PCP G 
 
 IV S P PSPP SP P S 3P 5PS 3PSS PSS PD SPCP G P 4P 4S SP P PSCP PCP G 
 
 III SPSPPSP PS 2P5P 3P PS PD PCSG P3PS3S PSP CPPCPG 
 
 II SSPSSP P S SP4PSPPS PS PD SCSG P3PS3S PSP CPPC G 
 
 18 
 
Figure 15. — Balanus trigonus. Antenna of stage V (A); mandible of 
 stage V (B). Scale = 0.1 mm. 
 
 setae are well developed on stages V and VI Mn (Fig. 15); 
 one terminal endopod is denticulate in these stages, a 
 feature not observed in other species described. 
 
 The AP is shorter than the DTS in stages IV- VI (Fig. 
 16a-c), but is about equal in length for stages V and VI 
 (Fig. 16d-e). Abdominal spination is typical in stages II- 
 IV (Fig. 16A-C); stage IV has one median spine. Series 
 two spines of stage V (Fig. 16D) consist of two pairs; one 
 large and one small median spines are also present. 
 
 The trilobed lb has a distinctly longer median lobe in 
 all stages (Fig. 16F). No teeth or denticulation is evident 
 on labral margins. 
 
 Balanus trigonus larvae are large relative to most 
 warm-water species; only Chelonibia patula larvae at- 
 tain a similar size for South Carolina species (Table 15). 
 In addition to the generally large size, the broad yet rela- 
 tively flat shield with well-developed ps spines distin- 
 guish later stage nauplii. Stage II nauplii have "swept 
 back" fh similar to B. amphitrite but B. trigonus larvae 
 are distinctly larger. 
 
 Conopea galeata (Linnaeus) 
 
 Conopea galeata is a commensal on gorgonians and is 
 restricted to warmer waters. In the western Atlantic it oc- 
 curs as far north as North Carolina (McDougall 1943). 
 Dead individuals are common on gorgonian branches 
 washed ashore on South Carolina beaches. Several 
 gravid individuals were dredged from tidal creeks at 
 North Inlet, but most gorgonians collected within the in- 
 let are free of commensal cirripeds. 
 
 Larvae of C. galeata have been reared and described 
 by Molenock and Gomez (1972) using adults collected on 
 the California coast. Present rearing attempts yielded 
 stages I-V; stage VI and the cyprid were not obtained. 
 For the stages obtained, no significant variation was ob- 
 served relative to Pacific larvae. 
 
 All Atlaritic larvae were within size ranges cited by 
 Molenock and Gomez (1972). Assuming VI and cyprid 
 stages also fall within these ranges, the mean sizes of C. 
 galeata larvae closely resemble those for B. venustus lar- 
 vae (see Table 15). 
 
 The stage I nauplius (Fig. 17A) shows no distinguish- 
 ing characteristics. Stage II nauplii are quite distinc- 
 tive; the shield has numerous short lateral spines (Fig. 
 17B) and a large median dorsal spine (Fig. IB). Later 
 stages have two large dorsal spines (Fig. IF) and nu- 
 merous lateral spines. Frontolateral horns are long and, 
 in stages III- VI, directed forward. Posterior shield spines 
 are long and curve slightly outward. 
 
 The AP spination differs little from the normal bala- 
 nid pattern. A single pair of series one spines is present 
 in stages II and III, however, additional spines are well 
 developed on the furcal spine (Fig. 17F, H). Series two 
 spines consist of one lateral pair and one median spine in 
 stage IV, two lateral pairs and one median spine in stage 
 V, and six lateral pairs in stage VI. One pair of series 
 three spines are present in stages V and VI. 
 
 The trilobed lb (Fig. 17E) has a distinctly longer me- 
 dian lobe. A small spine is present on the median lobe of 
 stages II-V in Atlantic larvae and assumed to be also 
 present in stage VI. 
 
 Setation observed agrees closely with the formulae 
 given by Molenock and Gomez (1972). With the excep- 
 tion of only 10 plumose setae on the endopod of stage V 
 An2 and 11 plumose setae on stage VI, the formulae for 
 C. galeata are the same as that for B. amphitrite (Table 
 8). Plumodenticulate setae not noted by Molenock and 
 Gomez were observed on the mandibular endopod. 
 
 Larvae of C. galeata most closely resemble B. venus- 
 tus larvae. The large dorsal spine(s) present in all but 
 stage I nauplii readily distinguishes this species from 
 other North Inlet larvae. 
 
 Chelonibia patula Ranzani 
 
 Chelonibia patula is cosmopolitan in tropical and 
 temperate waters. On the eastern coast it is not nor- 
 mally found much north of the Delaware Bay. Originally 
 reported only from the carapace of crabs (Pilsbry 1916), 
 
 19 
 
Figure 16.— Balanus trigonus. Abdominal process of naupliar stage II (A, a), III (B, b), IV (C, c), V 
 (D, d), VI (E, e); labrum of naupliar stage IV (F). Scales = 0.1 mm. 
 
 the species will also settle on shells (Pilsbry 1953). In 
 North Inlet, it is quite common on horseshoe crabs and 
 often found on portunid and spider crabs. Large healthy 
 specimens were also found on hermit crab shells, sup- 
 porting Pilsbry 's later observation. 
 
 Coker (1902) reported rearing barnacle larvae from 
 adult acorn barnacles attached to blue crabs, but neither 
 the species nor results were documented further. 
 Lacombe (1973) attempted to rear C. patula but ob- 
 
 tained only stages I-III. I reared two separate hatches to 
 cyprid stage. As this represents the first complete larval 
 development reported for this genus, a detailed descrip- 
 tion follows. 
 
 Stage I. (Fig. 18B). Rather robust and large with dark 
 brown pigment outlining gut region. Otherwise larvae are 
 typically pear-shaped with folded fh and rudimentary 
 AP. 
 
 20 
 
Figure 17. — Conopea galeata. Shield outlines of naupliar stages I-IV (A-D); labrum of stage IV (E); lateral 
 view of stage IV dorsal shield spines, DTS, AP (F); abdominal process of stage II (G), IV (H). Scale = 0.1 mm. 
 
 Figure 18.— Chelonibia patula. Egg ready to hatch (A); shield outlines of naupliar stages I- VI (B-G); cara- 
 pace profile of cyprid (H). Scale = 0.1 mm. 
 
 21 
 
Stage II. (Fig. 18C). Cephalic shield outline is nearly 
 circular with a highly arched back. Frontolateral horns 
 are long with a slight forward orientation. Pigment 
 around gut is present and persists in all naupliar stages. 
 
 Stage III. (Fig. 18D). Similar to stage II; anterior 
 shield margin less convex and fh wider with split tip. 
 Maxillules are present. The Anl has one preaxial seta. 
 
 Stage IV. (Fig. 18E). Posterior shield margin present 
 with short closely spaced ps spines. The Anl has two pre- 
 axial setae. 
 
 Stage V. (Fig. 18F). Similar to stage IV. Series three 
 spine present on AP. The Anl has three preaxial setae. 
 
 Stage VI. (Fig. 18G). Posterior shield region some- 
 what elongated and narrow. Compound eyes are present 
 after 1-2 days. The AP has six pairs of series two spines. 
 
 Cyprid. (Fig. 18H). Large and wide with relatively 
 well-developed compound eyes. Anterior ventral cara- 
 pace margin tends to have straight margin while an- 
 terior dorsal margin is rounded. 
 
 The shield in all stages lacks lateral or dorsal spines, is 
 broad and nearly circular, and has a highly arched dor- 
 sal surface. A distinct dark brown pigment area rings the 
 gut in all naupliar stages (Fig. 34A). 
 
 Setal numbers closely follow the normal balanid pat- 
 tern (Table 4) however, setal types vary (Table 10). All 
 Anl preaxial setae are simple and only one Anl terminal 
 seta is plumose in stages HI- VI (Fig. 19). This is in 
 marked contrast to all other North Inlet species in which 
 some preaxial setae are plumose and three (rarely two) 
 terminal setae are plumose in later naupliar stages. The 
 An2 (Fig. 20) setation is typical, although terminal setae 
 of the endopod have less plumose types than observed in 
 most species. The Mn (Fig. 21) terminal exopod seta is 
 particularly stout with dense long setules on the basal re- 
 gion of the shaft. The first postaxial setal group of the 
 endopod has two distinct plumodenticulate setae in 
 stages IV- VI (Fig. 21D). 
 
 The AP is distinctly shorter than the DTS only in stage 
 II. In later stages the AP is subequal or longer (Fig. 22). 
 The AP spination is not typical. In addition to what nor- 
 mally is considered the series one lateral spine pair, 
 stages II and III have an additional spine pair on the fur- 
 cal stem (Fig. 22 A, B). Stage PV has one lateral pair of 
 series two spines and a complex of two small median 
 spines and numerous spinules (Fig. 22C). Stage V has 
 one lateral pair of series two and series three spines and a 
 complex of two lateral pairs and small median spines 
 (Fig. 22D). This latter complex of spines in stages IV and 
 V appears to represent spines not normally described in 
 balanid species (Norris and Crisp 1953; Moyse 1961). 
 
 Figure 19.- 
 
 -Chelonibia patula. Antennules of naupliar stages I-VI 
 (A-F). Scale = 0.1 mm. 
 
 The trilobed lb is typical in form for Balanus spp. (Fig. 
 22F-H). The longer median lobe lacks spines or denticu- 
 lation in all stages. 
 
 Larvae are quite large for tropical species and have the 
 largest average size of described North Inlet species (see 
 Table 15); only Balanus trigonus has larvae of com- 
 parable size. The large well-rounded carapace and pig- 
 mented gut region readily distinguish C. patula nauplii 
 from other Carolina species of cirripeds. The size (see 
 Table 16) and large compound eye of the cyprid may be 
 sufficient to identify this stage. 
 
 Chthamalus fragilis Darwin 
 
 Chthamalus fragilis occurs from Cape Cod south to the 
 West Indies (Newman and Ross 1976), normally on up- 
 per intertidal substrates. In North Inlet, C. fragilis is 
 most common on hard substrates (wood, plastic, con- 
 crete, etc.) at the highest intertidal levels, but scattered 
 individuals are often intermixed with B. amphitrite and 
 B. eburneus at lower levels. It is also commonly found on 
 Spartina leaves and stalks. 
 
 Table 10. — Setation formulae for nauplii of Chelonibia patula. 
 
 Stage 
 
 Anl 
 
 An2 
 
 Mn 
 
 VI SS SSSPSSPPPSS 3P9P 
 
 V SS SSSPSSPSP S 2P8PS 
 
 IV SS SSPSSP P S 2P6PS 
 
 m s sspssp p s P6P 
 
 n sspssp ps ssps 
 
 2PSSPSPPPPPSCPG P5P SSSSSDSDPSCPPCPG 
 2PS SP SPP PP PSCP G P4PS SSSSSDSDPSCPPCPG 
 
 2PSSSSPSPPPSCPG P4P 
 2PS SP PPPSCPG P3PS 
 2PS SP PPPSC G P3PS 
 
 SSSSSD DPSCPPCPG 
 3S P SP CPPCPG 
 3S P SP CPPCPG 
 
 22 
 
^f>>^r 
 
 Figure 20. — Chelonibia patula. Antennae of naupliar stages I-VI (A-F). Scale = 0.1 mm. 
 
 Larvae of the closely related C. stellatus have been de- 
 scribed (Table 2), but no published descriptions of C. 
 fragilis exist. 
 
 The nauplii and cyprid of C. fragilis are small; average 
 measurements are the smallest of South Carolina spe- 
 cies (see Table 15). Since the AP of later stages usually 
 contracts beneath the posterior carapace margin, total 
 lengths for stages IV- VI have been omitted. 
 
 Stage I nauplii are small and typically pear-shaped 
 (Fig. 23A). However, stage II and later stages have a 
 broad nearly round shield with very short fh somewhat 
 folded under the as margin (Fig. 23G-F).The shield has a 
 highly arched back (Fig. 23b d) and late stages appear 
 "globular." No shield spines are present and the ps 
 spines typical of balanids are lacking. The cyprid (Fig. 
 23G) is similar to B. eburneus or B. amphitrite but 
 smaller (see Table 15). 
 
 Setal counts of the Anl and Mn follow the balanid pat- 
 tern (Table 4). The Anl (Fig. 24A) terminal setae vary 
 
 between SSPS or PSPS in later stages (Table 11), a 
 situation unique to South Carolina species observed. The 
 An2 (Fig. 24B) is unique, having hispid setae, large num- 
 bers of postaxial endopod setae (Table 11) and "fea- 
 thered" or "downy" plumose setae. The Mn (Fig. 24C) 
 cuspidate setae have dense setulation (Fig. 31) relative to 
 equivalent setae in balanids (Fig. 3H). Plumose setae as- 
 sociated with the cuspidate setae also have dense setules 
 but are not "feathered." 
 
 The AP of stages II and III is short with strong furcal 
 spines and large series one spines (Fig. 25A, B). Later 
 stages depart from AP configuration of balanids. In stage 
 IV, one pair of large spines splits from the furcal stem. 
 The resulting configuration appears as four terminal 
 spines or processes (Fig. 25C). In addition, two pairs of 
 lateral spines are evident on the abdominal region. Stage 
 
 V is similar, but an additional pair of median spines is 
 present between the terminal processes (Fig. 25D). Stage 
 
 VI (Fig. 25E, F) also has six terminal processes and two 
 
 23 
 
Figure 21.— Chelonibia patula. Mandibles of naupliar 
 stages I-VI (A-F). Scale = 0.1 mm. 
 
 pairs of lateral spines and, in addition, four pairs of me- 
 dian spines are present. The DTS is longer than the AP 
 in stages II and III (Fig. 23b), subequal in stage IV (Fig. 
 23d), and very short or rudimentary in stages V and VI 
 (Fig. 26F). 
 
 The lb is unilobed. Stages II and III have one pair of 
 larger lateral teeth separated by numerous small denti- 
 cules (Fig. 26A). The denticles are lost in stage IV (Fig. 
 26B) and a median porelike protuberance becomes in- 
 creasingly developed in the late stages (Fig. 26C). 
 
 Chthamalus fragilis larvae have features noted as typi- 
 cal for other larvae of the genus: no ps spines; fh folded 
 under the shield; a carapace nearly as broad as long; a 
 unilobed lb; and hispid and feathered setae (Sandison 
 1967). 
 
 The general appearance of the nauplii and small size of 
 the cyprid make larvae of this species quite easy to dis- 
 tinguish in North Inlet, where no other chthamalid spe- 
 cies occur. 
 
 Octolasmis muelleri (Coker) 
 
 Octolasmis muelleri is a small pedunculate barnacle 
 found attached to the gills of the blue crab, Callinectes 
 sapidus, and other decapod hosts (Walker 1974b). First 
 described from Beaufort, N.C., by Coker (1902), 0. 
 muelleri is perhaps synonymous to the cosmopolitan 
 Octolasmis lowei (Nilsson-Cantell 1927; Causey 1961) or 
 a local race or subspecies (Pilsbry 1953) of a shallow-wa- 
 ter 0. lowei-series (Table 12). In the western Atlantic its 
 known range extends southward from the Chesapeake 
 Bay through the Gulf of Mexico and Caribbean Sea to 
 Brazil (Lang 1976). 
 
 The complete larval development of this species has 
 been recently described using larvae released from North 
 Inlet adults (Lang 1976). An additional octolasmid spe- 
 cies, Octolasmis forrestii (Stebbing), has subsequently 
 been obtained from the gills of a spiny lobster captured 
 in Belize, Central America; released larvae were suc- 
 
 24 
 
Figure 22. — Chelonibia patula. Abdominal process of 
 stage II (A, a), III (B, b), IV (C, c), V (D, d), VI (E); 
 labrum of stage II (F), IV (G), VI (H). Scale = 0.1 mm. 
 
 cessfully reared through stage VI nauplius. A brief com- 
 parative account of the larval development of both Octo- 
 lasmis species follows; for details see Lang (1976). 
 
 Larvae of 0. forrestii are quite similar to O. muelleri 
 (Figs. 27, 28). The nauplius cs is small and triangular 
 and develops small blunt lateral spines in later stages. 
 The AP and DTS are considerably longer than the shield, 
 and the fh are also quite long. In both species develop- 
 ment of the ps border is delayed until stage V. 
 
 The appendages of octolasmid nauplii are distinctive. 
 The Anl and An2 are elongate relative to balanomorph 
 nauplii while the Mn is small with a poorly developed 
 exopod (see Figs. 33A, 34C). Setation of 0. forrestii 
 nauplii differ from those of 0. muelleri (Table 13) only at 
 stage IV (Fig. 29). Bristled setae (Fig. 3M) are present on 
 the Anl (Fig. 29A); development of setae at each molt, 
 however, follows a pattern similar to balanomorph 
 nauplii. The An2 exopod setae are long and delicate; un- 
 like balanomorph species, setules are restricted to one 
 side of the shaft for these setae. The Mn (Fig. 29C) shows 
 little increase in size during molts; exopod setation 
 (Table 13) is significantly reduced in later stage nauplii 
 relative to all other described planktotrophic cirriped 
 nauplii. 
 
 The AP and DTS of octolasmid nauplii are extremely 
 long, a feature also seen in Lepas nauplii (see Fig. 30). 
 
 Unlike Lepas nauplii, larvae of both Octolasmis species 
 lack abdominal spines. 
 
 The lb of 0. muelleri and 0. forrestii is unilobed and 
 tapers to a median porelike structure. No teeth or den- 
 ticulation were observed (Fig. 29D). 
 
 Development of 0. forrestii nauplii incorporates the 
 same unique features described for 0. muelleri (Lang 
 1976). Morphology and naupliar size of these two species 
 varies little; identification to species from field samples 
 would be virtually impossible in areas where numerous 
 Octolasmis species occur. In coastal Carolina waters, 
 however, 0. muelleri is the only octolasmid species com- 
 monly present. Only Lepas nauplii are similar in ap- 
 pearance; size and lb morphology easily distinguish these 
 larvae. Although the nauplii of 0. muelleri are distinc- 
 tive, the cyprid (see Fig. 36C) closely resembles Balanus 
 amphitrite-complex cyprids. Identification is possible 
 based on the symmetric carapace profile of 0. muelleri 
 cyprids as opposed to the enlarged anterior region and ta- 
 pered posterior region common to Balanus species. 
 
 Lepas spp. 
 
 Five species of Lepas are commonly found in the west- 
 ern Atlantic (Zullo 1963). All are open water neustonic 
 forms whose occurrence in coastal waters is usually 
 
 25 
 
Figure 23.— Chthamalus fragilis. Shield outlines of naupliar stages I- 
 VI (A-F); lateral profile of stage II (b), IV (d); carapace outline of 
 cyprid (G). Scales = 0.1 mm. 
 
 restricted to introduction by ships or floating debris 
 directed shoreward by storms. Collections on South 
 Carolina beaches following storms have produced Lepas 
 anatifera on driftwood and L. anserifera, L. pectinata, 
 and L. fascicularis on sargassum. Lepas hilli, although 
 not observed in present collections, should also occur on 
 occasion. 
 
 Although breeding populations of Lepas are not com- 
 monly found in coastal waters, circumstance introduc- 
 tion of gravid adults may result in local release of Lepas 
 larvae. The complete larval development of L. fascicu- 
 laris has been reconstructed from plankton samples 
 (Willemoes-Suhm 1876; Bainbridge and Roskell 1966). 
 John Moyse reared nauplii of L. pectinata and L. anati- 
 fera (pers. commun.) but larvae remain undescribed. In 
 present studies up to stage V nauplii of L. pectinata and 
 stage ITJ nauplii of L. anserifera have been reared from 
 gravid adults washed ashore. Larvae obtained are quite 
 similar to those described for L. fascicularis. Staging of 
 
 Figure 24. —Chthamalus fragilis. Antennule of stage IV (A); anten- 
 na of stage IV (B); mandible of stage IV (C). Scale = 0.1 mm. 
 
 Lepas larvae is not difficult (see Bainbridge and Roskell 
 1966); however, identification of nauplii to species must 
 await further descriptions of Lepas larvae. Using L. pec- 
 tinata as an example, general features of Lepas nauplii 
 are outlined below. 
 
 Lepas nauplii have very long fh, a DTS, and an AP 
 (Fig. 30A-C). The shield of stage II nauplii is plain (Fig. 
 
 Table 11. — Setation formulae for nauplii of Chthamalus fragilis. 
 
 Stage 
 
 Anl 
 
 An2 
 
 Mn 
 
 VI SPPPSPP SPPPSS 4P8P 
 
 V SPPPSPP S SPSP S 4P7P 
 
 IV SPPSPP S SP P S 3P6P 
 
 m SPSPS P SP P S 2P5P 
 
 n ssps ss p s SP4PS 
 
 PPSPP PSSSS SFFF SPFH G P5P SSSS SPSP PSCP PPC G 
 
 PPSPPPSSS SFFF SPFH G P4PS 4S SPSP PSCP PPC G 
 
 PPSPSPSS SFF SPFHG P4P 4S SP P PSCP PPC G 
 
 PP P PSS FF SFHG P3PS 4S SP P CPPPCG 
 
 PP S SS FF SFHG P3PS 3S SP P CP PC G 
 
 26 
 
Figure 25. — Chthamalus fragilis. Abdominal process of stage II (A), 
 HI (B), IV (C), V (D), VI (E); lateral profile of stage VI nauplius (F). 
 Scale = 0.1 mm. 
 
 30A, B). Later stages have dorsal and lateral shield spines 
 and often appear quite "ornate" (Fig. 30C). The densely 
 spinose AP is highly arched in early stage nauplii (Fig. 
 30A, B); abdominal spines are present (Fig. 30D, E) and 
 may be used to stage nauplii (Bainbridge and Roskell 
 1966). The lb is broad edged with one or more pair of 
 teeth (Fig. 30F). Setation includes bristled setae on the 
 Anl (Fig. 30G) and feathered setae on the An2 (Fig. 
 30H). The Mn is well developed with notably long 
 postaxial endopod setae (Fig. 301). 
 
 Figure 26. — Chthamalus fragilis. Labrum 
 of stage III (A), IV (B), VI (C). Scale = 0.1 
 
 Nauplius SC 
 
 Examination of plankton samples taken 2 to 35 mi off 
 Georgetown Harbor, S.C., during October 1976, yielded 
 stages II-VI of an undescribed cirriped larva. The pre- 
 dominant barnacle larvae present in all samples ex- 
 amined have been designated "nauplius SC." 
 
 The elongate form (Fig. 31) and size (see Table 15) of 
 nauplius SC resembles Octolasmis larvae, however, the 
 AP (Fig. 31) varies significantly. The fh are moderate in 
 length and directed rearward. Basic morphological 
 changes at each molt closely follow the expected balanid 
 pattern. 
 
 Setation (Table 14) is unique. The Anl (Fig. 32A) is 
 typical and shows a normal setation progression at each 
 molt. The An2 (Fig. 32B) endopod has feathered setae 
 and large numbers of setae in later stage nauplii. The Mn 
 (Fig. 32C) is well developed with typical setation pat- 
 terns. 
 
 The DTS is long in all naupliar stages, a feature also 
 seen in Lepas, Octolasmis, and Verruca (LeReste 1965) 
 
 Table 12. — Structure of the Octolasmis lowei-complex. 
 
 Synonyms of Octolasmis lowei Darwin-Nilsson-Cantell (1927) 
 
 Dichelaspis lowei Darwin, 1851 
 Dichelaspis darwini Filippi, 1861 
 Dichelaspis aymonini Lesson, 1874 
 Dichelaspis neptuni Mac Donald, 1869 
 Dichelaspis sinuata Aurivillius, 1894 
 Dichelaspis trigona Aurivillius, 1894 
 Dichelaspis mulleri Coker, 1902 
 Dichelaspis vaillantii Gruvel, 1902 
 Octolasmis geryonophila Pilsbry, 1907 
 
 Madeira 
 Mediterranean 
 Japan 
 Australia 
 Java Sea 
 Java Sea 
 North Carolina 
 Suez 
 Atlantic 
 
 Subsequent Modifications and Additions 
 
 O. ay monini -reinstated as species Hiro (1937) 
 
 0. brein's-Pearse, 1951 added as synonyms Newman (1961) 
 
 O. urccus-Pearse, 1951 
 
 0. reeptum'-reinstated as species Newman (1961) 
 
 0. geryonophila-changed to synonym of O. aymonin Newman (1967) 
 
 27 
 
Figure 27. — Octolasmis muelleri. Shield outlines of naupliar stages I-VI (A-F); cyprid (G). Scale = 0.1 mm. 
 
 Figure 28. — Octolasmis forrestii. Shield outlines of naupliar stages I-VI (A-F). Scale = 0.1 mm. 
 
 28 
 
Table 13. 
 
 — Setation formulae for 
 
 nauplii 
 
 of Octolasmia muelleri. 
 
 Stage 
 
 Anl 
 
 An2 
 
 Mn 
 
 VI SP PSBSSBPB S3P7P 4P 2PSSSCGSSS 3SCPPPPPG 
 
 V SP PSBSSBSB S2P7P 4P 2PSSSCGSSS 3SCPPPPPG 
 
 IV PP SBSSB B 2P 5P2S 3PS PS S SSC G SS 3SCPPPPPG 
 
 m P SPSS B B 2P 5P 3P P S S C G SS 3S CPP PPP G 
 
 II SPSSB B SP 4PS 2PSS SS CG SS 3SCPPPP ? 
 
 I SSSS S S SS SSS 3S S S G SS SS SSS SS 
 
 Figure 29. — Octolasmis forrestii. Antennule of stage 
 IV (A); antenna of stage IV (B); mandible of stage IV 
 (C); labrum of stage IV (D). Scale = 0.1 mm. 
 
 nauplii. The AP, however, is unique; a narrow stem is ab- 
 sent as the basal region splits directly into the furcal pro- 
 cesses (Fig. 31). Abdominal spination is restricted to one 
 large median spine in stages II-V (Fig. 31A-D) and six 
 smaller paired spines in stage VI (Fig. 31E, e). 
 
 The lb (Fig. 31) is unilobed and tapers to a blunt den- 
 ticulate tip in all stages. 
 
 Larvae of this unknown species were not found within 
 North Inlet or Winyah Bay but were common (in Octo- 
 ber) in nearshore waters. The general body form and uni- 
 que AP structure of this nauplius readily distinguishes it; 
 however, larvae of this species do not closely match lar- 
 vae of any presently described family (Table 2). Possible 
 affinities of these nauplii are discussed later. 
 
 Hansen (1899) described 10 "species" of cirriped 
 nauplii from material collected by the Plankton- 
 Expedition. Based on carapace, DTS, and labrum mor- 
 phology, Hansen's "nauplius" may represent stage III 
 and IV of nauplius SC or at least a closely related species. 
 Similarly "naupliusa" probably represents a stage VI 
 Balanus trigonus nauplii and "nauplius/3" appears to be 
 stage IV and VI Balanus amphitrite nauplii. However, 
 
 since Hansen did not describe appendages and other 
 naupliar detail, comparisons with present descriptions 
 are tenuous. 
 
 KEYS TO THE BARNACLE LARVAE 
 OF THE CAROLINAS 
 
 Assigning Stages 
 
 Based on reared and planktonic material, it is possi- 
 ble to construct a key to the predominant barnacle 
 nauplii of the Carolina coastal waters. The key is limited 
 to naupliar stages II- VI: stage I nauplii show little 
 morphological variation and are rarely encountered in 
 plankton samples while many cyprids (see page 36) can- 
 not be reliably identified to species. A two-step proce- 
 dure is followed. Since each naupliar stage often has its 
 own set of morphological features and size ranges, 
 nauplii must first be accurately "staged." Different keys 
 for each stage or group of stages are then used to identify 
 the species of the nauplius. 
 
 29 
 
Figure 30. — Lepas pectinata. Shield outline of naupliar stage II (A); shield outline (B) and lateral profile (b) of stage III; shield outline (C) and 
 lateral profile (c) of stage IV; abdominal spines of stage II (D) and stage IV (E); labrum of stages II and IV (F); antennuleof stage IV (G); anten- 
 na of stage IV (H); mandible of stage IV (I). Scales = 0.1 mm. 
 
 Morphological features cited below for assigning stages 
 of barnacle nauplii are shown in Figure 4. Abdominal 
 process characters normally apply only to balanomorph 
 larvae; other features are valid for all larvae except 
 Octolasmis. In this case only the setation of the Anl is 
 valid. See Figures 1 and 4 for a complete list of terms and 
 abbreviations. 
 
 la. 
 
 lb. 
 
 2a. 
 2b. 
 
 Frontolateral horns folded back, AP rudi- 
 mentary Stage I 
 
 Frontolateral horns extended, AP well de- 
 veloped 2 
 
 Posterior shield margin absent 3 
 
 Posterior shield margin present 4 
 
 30 
 
Figure 31. — "Nauplius SC." Shield outlines of naupliar stages II-V1 (A-E) and lateral profiles of stages V (d) 
 
 and VI (e). Scale = 0.1 mm. 
 
 Table 14. — Setation formulae for nauplii Y. 
 
 Stage 
 
 Anl 
 
 An2 
 
 Mn 
 
 VI S P P PSPP PP P PS P 4P 8P 
 
 V SPPPSPPSPSP P 3P8P 
 
 IV SPPSPPSP P P 2P7P 
 
 III SPSPPSP P P 2P5P 
 
 PPSPPS PPPS SFFF PFSC G P5P PPSPPS PSPS SPCPPPPG 
 
 PPSPP PPP SFFF PFSC G P4PS PPSPP PSPS SPCPPPPG 
 
 PPSPS SPP SFF PFSCG P4P SPSPS PSP SPCPPPPG 
 
 PP P PP FF PFSCG P3PS SP SP P P PCPPPPG 
 
 II 
 
 SSPS SP S S 2S4PS PP S 
 
 SP FF SF CG P3PS SS S S P PCPPP G 
 
 3a. Frontolateral horn with plain tip, Anl 
 
 without preaxial seta Stage II 
 
 3b. Frontolateral horn with split tip, Anl 
 
 with one preaxial seta Stage III 
 
 4a. Compound eyes often present; thoracic 
 region with six pairs of median spines; 
 third Anl segment expanded Stage VI 
 
 4b. Compound eyes not present; thoracic re- 
 gion with 0-2 rows of spines; third Anl 
 segment not expanded 5 
 
 5a. Anl with two preaxial setae, AP with 
 
 series two spine pair Stage IV 
 
 5b. Anl with three preaxial setae, AP with 
 
 series two and series three spine pairs Stage V 
 
 Species Identification of Nauplii 
 
 Stage II nauplii are in many instances the most com- 
 monly encountered larval stage in plankton samples 
 (Lang see footnote 3) and for this reason complete figures 
 
 31 
 
Figure 32.— "Nauplius SC." Antennule of stage III (A); antenna of 
 stage III (B); mandible of stage III (C). Scale = 0.1 mm. 
 
 Figure 33. — Stage II nauplii of Balanus amphitrite- 
 complex species common in Carolina waters: Balanus 
 eburneus (A); B. improvisus (B); B. amphitrite am- 
 phitrite (C); B. subalbidus (D); B. venustus (E). Scale 
 = 0.1 mm. 
 
 32 
 
Figure 34. — Stage II nauplii of barnacle species found in Carolina waters: Lepas pectinata (A); Lepas anseri- 
 fera (B); Chelonibia patula (C); "nauplius SC" (D); Conopea galeata (E); Chelonibia patula (F); Chthamalus 
 fragilis (G); Balanus trigonus (H). Scale = 0.1 mm. 
 
 for common stage II nauplii are provided (Figs. 33, 34) 
 and the stage II key should be studied prior to use of later 
 stage keys. 
 
 The present keys should account for most barnacle lar- 
 vae found in shallow-water regions from Georgia to North 
 Carolina. As evident by "nauplius SC," some unde- 
 scribed nauplii can be expected, particularly in offshore 
 samples. Difficulties in species identification of nauplii, 
 for the most part, is limited to Balanus amphitrite-com- 
 plex species (Fig. 33). Early stages of B. eburneus, B. 
 improvisus, and B. amphitrite are particularly difficult 
 to distinguish and may be easily confused. 
 
 The size of nauplii, in many instances, provides rapid 
 clues to both stage and identity of the specimen, how- 
 ever, caution should be exercised. Laboratory rearing 
 clearly demonstrates that significant size differences in 
 larvae may be induced by the temperature of egg incu- 
 bation and/or larval rearing (Lang see footnote 3). Sizes 
 of nauplii (Table 15) and cyprid (Table 16) show that lar- 
 
 vae developing in warmer water tend to be smaller than 
 larvae of the same species developing in cooler water. 
 Summer and winter stage II nauplii of B. improvisus 
 from North Inlet plankton samples and summer larvae 
 from Rhode Island show considerable size variation; both 
 seasonal and geographical size variation should be ex- 
 pected. 
 
 Key to Stage II Nauplii of the Carolinas 
 
 la. Labrum unilobed (Fig. 26) 2 
 
 lb. Labrum trilobed 5 
 
 2a. Shield rounded, DTS shorter than 
 
 shield length (Fig. 34G) Chthamalus fragilis 
 
 2b. Shield triangular, DTS longer than 
 
 shield length 3 
 
 3a. Labrum with flat toothed edge (Fig. 
 
 35a, 34A, B) Lepas spp. 
 
 3b. Labrum tapered to blunt tip (Fig. 35A) 4 
 
 33 
 
Table 15.— Size ranges of barnacle nauplii obtained by laboratory rearing and plankton samples. Measurements represent millimeters/100 (38 
 = 0.38 mm); n = number measured, TL = total length, SL = shield length, W = width; SC = North Inlet, South Carolina; RI = Narragansett 
 Bay, Rhode Island. See Materials and Methods for diet symbols. 
 
 Species Source 
 
 Diet 
 Temp (°C). 
 
 Stage II 
 
 Stage III 
 
 Stage IV 
 
 Stage V 
 
 Stage VI 
 
 n TL W n TL W n TW SL W n TL SL W n TL SL W 
 
 Balanus 
 amphitrite 
 Balanus 
 eburneus 
 
 Balanus 
 improvisus 
 
 Balanus 
 
 subalbidus 
 
 Balanus 
 
 trigonus 
 
 Balanus 
 
 venustus 
 
 Chelonibia 
 
 patula 
 
 Conopea 
 
 galea t a 
 
 Chthamalus 
 
 fragilis 
 
 Octolasmis 
 
 muelleri 
 
 Nauplius SC 
 
 SC 
 
 SC 
 
 SC 
 
 SC 
 
 HI 
 
 SC 
 
 RI 
 
 SC 
 
 SC 
 
 SC 
 
 SC 
 
 RI 
 
 RI 
 
 SC 
 
 SC 
 
 SC 
 SC 
 
 TET/MON 
 25 
 
 TET/MON 
 25 
 
 Plankton 
 July 
 TET/3H 
 25 
 
 TET/MON 
 20 
 
 Plankton 
 Jan. 
 
 Plankton 
 Nov. 
 
 TET/MON 
 25 
 
 TET/MON 
 25 
 
 TET/MON 
 25 
 
 Plankton 
 July 
 
 TET/SKEL 
 20 
 
 Plankton 
 Oct. 
 
 3H/MON 
 25 
 
 (Molenoch and 
 Gomez 1972) 
 
 TET/MON 
 
 25 
 
 TET/MON 
 
 27 
 
 Plankton 
 
 Oct. 
 
 29 28-3412-16 
 
 10 32-3616-18 
 
 8 31-3315-17 
 
 15 28-3113-14 
 
 10 34-3716-18 
 
 10 35-3816-18 
 
 15 35-43 17-20 
 
 6 30-31 14-15 
 
 5 38-40 17-18 
 
 15 37-4017-19 
 
 4 38-40 17-18 
 
 10 34-3916-18 
 
 10 39-44 18-20 
 
 10 42-44 21-26 
 
 77 32-44 16-20 
 
 10 24-2617-18 
 
 8 79-85 10-77 
 
 2 42 12 
 
 27 31-3616-20 13 33-40 24-3017-23 
 
 10 36-41 18-23 10 42-45 30-33 23-25 
 
 7 37-41 20-22 10 28-32 22-24 
 
 10 32-38 16-19 10 41-46 29-32 24-27 
 
 10 37-43 19-21 10 41-46 29-32 25-28 
 
 2 38-41 19-20 
 
 5 32-3518-19 
 
 10 44-48 23-24 
 
 10 41-45 19-22 
 
 4 43-47 21-23 
 10 40-46 20-23 
 
 5 44-48 21-23 
 10 45-49 25-28 
 53 40-50 20-26 
 10 26-3017-20 
 10 92-111 12-14 
 
 8 48-51 15-16 
 
 6 36-45 29-3120-23 
 
 11 51-56 31-36 28-32 
 10 44-50 29-33 23-27 
 
 2 35-40 29-31 
 
 12 41-53 32-35 23-28 
 
 10 52-60 35-43 32-37 
 
 57 48-58 24-34 22-31 
 
 10 24-25 23-24 
 
 9 118-134 16-18 
 
 10 54-58 23-2518-19 
 
 12 40-47 28-25 24-28 10 47-57 34-39 27-32 
 
 15 46-57 33-44 26-32 15 57-62 39-46 32-37 
 
 7 37-40 28-30 1 42 40 
 
 10 52-62 37-4132-35 10 65-72 48-52 40-45 
 
 10 51-60 39-43 32-36 10 63-76 52-58 37-45 
 
 7 48-51 36-40 24-30 6 56-64 44-48 33-35 
 
 2 61-65 41-42 36-38 10 74-81 51-57 43-50 
 10 54-64 38-43 29-34 7 68-76 44-5134-37 
 
 3 40-4134-35 2 50-52 41-44 
 13 51-64 38-43 28-35 10 72-80 49-57 37-42 
 
 12 63-67 46-54 39-42 6 73-81 54-6142-50 
 
 45 56-74 34-44 30-37 33 60-86 42-58 36-48 
 
 8 30-3126-29 5 44-4719-24 
 6 167-182 32-36 23-27 9 254-278 52-55 36-39 
 6 61-67 26-30 22-24 5 66-74 36-38 26-28 
 
 Table 16. — Size of barnacle cyprids reared in the laboratory: SC = 
 North Inlet, South Carolina, RI = Narragansett, Rhode Island; n = 
 number measured. See Materials and Methods for diet abbreviations. 
 
 
 
 
 
 
 Width 
 
 Length 
 
 
 
 
 
 
 (microns) 
 
 Species ! 
 
 Source 
 
 Diet-Temp. 
 
 °C 
 
 n 
 
 x±sd 
 
 x±sd 
 
 Balanus amphitrite 
 
 SC 
 
 TET/MON 
 
 20 
 
 32 
 
 239±17 
 
 499±14 
 
 
 SC 
 
 TET/MON 
 
 25 
 
 38 
 
 214±17 
 
 477±22 
 
 Balanus eburneus 
 
 SC 
 
 TET/MON 
 
 20 
 
 12 
 
 247 ±08 
 
 547 ±16 
 
 
 SC 
 
 TET/MON 
 
 25 
 
 14 
 
 242±11 
 
 528±22 
 
 Balanus improvisus 
 
 SC 
 
 TET/MON 
 
 25 
 
 5 
 
 267 ±19 
 
 551 ±26 
 
 
 RI 
 
 TET/MON 
 
 20 
 
 10 
 
 257 ±24 
 
 573 ±16 
 
 Balanus trigonus 
 
 SC 
 
 TET/MON 
 
 25 
 
 7 
 
 264 ±19 
 
 570 ±27 
 
 Balanus venustus 
 
 SC 
 
 TET/MON 
 
 25 
 
 6 
 
 235 ±10 
 
 545 ±08 
 
 
 RI 
 
 TET/MON 
 
 20 
 
 16 
 
 243 ±16 
 
 572 ±34 
 
 Chelonibia patula 
 
 SC 
 
 TET/MON 
 
 25 
 
 10 
 
 262 ±05 
 
 648 ±30 
 
 Chthamalus fragilis 
 
 SC 
 
 TET/MON 
 
 25 
 
 25 
 
 217±22 
 
 456 ±25 
 
 Octolasmis muelleri 
 
 SC 
 
 TET/MON 
 
 27 
 
 10 
 
 223±21 
 
 572 ±25 
 
 4a. Abdominal process long, furcal lobes 
 absent or poorly developed (Fig. 35B, 
 34C) Octolasmis muelleri 
 
 4b. Abdominal process short, furcal lobes 
 
 long (Fig. 35b, 34C) "nauplius SC" 
 
 5a. Shield with dorsal and lateral spines 6 
 
 5b. Shield without dorsal and lateral spines 7 
 
 6a. Dorsal shield spine long (Fig. 34E) C. galeata 
 
 6b. Dorsal shield spine short (Fig. 33E) 
 
 B. venustus 
 
 7a. Frontolateral horn tips directed distinctly 
 
 forward (Fig. 35C) 8 
 
 7b. Frontolateral horn tips perpendicular to 
 shield median axis or directed rearward 
 (Fig. 35c) 10 
 
 8a. Larva greater than 200 Mm wide, circular 
 
 shield (Fig. 34F) C. patula 
 
 8b. Larva less than 200/um wide, shield ellip- 
 tical 9 
 
 9a. Labrum with distinct teeth on median 
 
 lobe (Fig. 33B) B. improvisus (summer) 
 
 9b. Labrum without distinct teeth on median 
 
 lobe (Fig. 33A) B. eburneus 
 
 10a. Frontolateral horns very short (Fig. 
 
 33D) B. subalbidus 
 
 10b. Frontolateral horns normal 11 
 
 34 
 
Figure 35. — Morphological features of Carolina barnacle nauplii: 
 labrum of Octolasmis (A) and Lepas (a); AP and DTS of Octolasmis 
 (B) and "nauplius SC" (b); forward orientation (C) and perpendicu- 
 lar orientation (c) of frontolateral horns; frontolateral horns and AP- 
 DTS configuration of Balanus subalbidus (D) and B. a. amphitrite 
 (d); stage IV carapace outlines of B. subalbidus (E), B. amphitrite 
 (F), B. eburneus (H), and B. trigonus (G). (See naupliar keys for de- 
 tails.) 
 
 11a. Larva less than 340 ^m wide, lateral 
 shield margin somewhat straight with one 
 pair of small rounded spines (Fig. 
 33c) B. amphitrite 
 
 lib. Larva more than 340 nm long, lateral 
 
 shield margins rounded 12 
 
 12a. Frontolateral horns perpendicular to body 
 axis or directed slightly anteriorly, lb 
 
 median lobe with teeth (Fig. 33B) 
 
 JB. improvisus (winter) 
 
 12b. Frontolateral horns curved slightly poste- 
 riorly, lb median lobe without teeth (Fig. 
 34H) B. trigonus 
 
 Key to Stage III Nauplii of the Carolinas 
 
 la. Labrum unilobed as in stage II key 
 
 lb. Labrum trilobed 5 
 
 5a. Shield with paired dorsal spines 6 
 
 5b. Shield without dorsal spines 7 
 
 6a. Dorsal shield spines long, approximate 
 
 length of fh C. galeata 
 
 6b. Dorsal shield spines very short B. venustus 
 
 7a. Shield wide (over 250 ^m) and round C. patula 
 
 7b. Shield narrow (less than 250 /xm) 8 
 
 8a. Frontolateral horns directed perpendic- 
 ularly or rearward 9 
 
 8b. Frontolateral horns directed distinctly 
 
 forward 10 
 
 9a. Frontolateral horns very short and straight, 
 
 AP less than half the length of the DTS 
 
 (Fig. 35D) .„ B. subalbidus 
 
 9b. Frontolateral horns curved rearward, AP 
 
 one-half length of DTS (Fig. 35c) . . .B. amphitrite 
 10a. Abdominal process one-half length of 
 
 DTS or less, fh extend straight B. eburneus 
 
 10b. Abdominal process over one-half length 
 
 of DTS, fh bend at tips 11 
 
 11a. Labrum with teeth on median lobe, larvae 
 
 less than 440 nm in length B. improvisus 
 
 lib. Labrum without teeth, larva over 440 /una 
 
 in length B. trigonus 
 
 Key to Stages IV-V Nauplii of the Carolinas 
 
 la. 
 lb. 
 5a. 
 5b. 
 6a. 
 
 6b. 
 
 7a. 
 7b. 
 
 8a. 
 
 8b. 
 9a. 
 
 9b. 
 
 10a. 
 
 10b. 
 11a. 
 
 lib. 
 
 Labrum unilobed as in stage EI key 
 
 Labrum trilobed 5 
 
 Shield with dorsal spines 6 
 
 Shield without dorsal spines 7 
 
 Long paired dorsal shield spines, distinct 
 
 lateral spines C. galeata 
 
 Very short paired dorsal shield spines, 
 
 spinulose shield margins B. venustus 
 
 Shield nearly as wide as long, PS spines 
 
 short, Anl with SPPS terminal setae . .C. patula 
 
 Shield longer than wide, Anl with PSPP 
 
 terminal setae 8 
 
 Frontolateral horn tips perpendicular or 
 
 directed rearward 9 
 
 Frontolateral horn tips directed forward 10 
 
 Frontal horns short, PS spines long, AP 
 less than one-half length of DTS (Fig. 
 
 35E) B. subalbidus 
 
 Frontolateral horns short to moderate, PS 
 spines short, AP one-half length of DTS 
 
 (Fig. 35F) B. amphitrite 
 
 Abdominal process subequal or longer 
 
 than DTS B. improvisus 
 
 Abdominal process shorter than DTS 11 
 
 Posterior shield spines long, stage V with 
 
 five median spines on AP (Fig. 35G) . B. trigonus 
 
 Posterior shield spines moderate to short, 
 
 stage V with three median AP spines (Fig. 
 
 35H) B. eburneus 
 
 Key to Stage VI Nauplii of the Carolinas 
 
 la. Labrum unilobed as in stage II key 
 
 lb. Labrum trilobed 5 
 
 5a. Shield with two dorsal spines C. galeata 
 
 5b. Shield without dorsal spines 6 
 
 6a. Abdominal process subequal or longer 
 
 than DTS 7 
 
 6b. Abdominal process shorter than DTS 8 
 
 35 
 
7a. Antennules with SPSS terminal setae ...C.patula 
 
 7b. Antennules with PSPP terminal setae 9 
 
 8a. Posterior shield spines longer than fh 
 
 B. subalbidus 
 
 8b. Posterior shield spines equal or shorter in 
 
 length than the fh 10 
 
 9a. Shield length greater than 560 jum B. trigonus 
 
 9b. Shield length less than 560 nm B. improvisus 
 
 10a. Antennae with 11 setae on exopod .... B. uenustus 
 
 10b. Antennae with 12 setae on exopod 11 
 
 11a. Shield length generally greater than 400 
 
 /um, fh tip extends straight B. eburneus 
 
 lib. Shield length generg less than 400 /urn, 
 
 fh tip bent rearward B. amphitrite 
 
 Cyprids 
 
 Cyprid larvae are vpp similar in most barnacle spe- 
 cies. Size (Table 16) aii even length to width ratios of 
 the carapace (Fig. 36E, F) vary with rearing conditions 
 (Lang see footnote 3). Present studies have failed to find 
 reliable means to identify B. amphitrite-complex cyprids 
 to species. Although Chthamalus fragilis cyprids (Fig. 
 36B) tend to be smaller, even this species may be con- 
 fused with cyprids of B. amphitrite. 
 
 Octolasmis cyprids (Fig. 36C) are "bean"-shaped with 
 little size difference in anterior and posterior carapace 
 regions; fresh specimens have a distinct bright orange 
 pigment (Lang 1976). 
 
 Chelonibia patula cyprids (Fig. 36A) are the largest 
 larvae of balanomorph species in the Carolinas (Table 
 16). The large compound eye is distinctive. 
 
 Balanus trigonus (Fig. 36D) are also large but have a 
 small compound eye. The carapace is "teardrop" in 
 shape with well-rounded margins. 
 
 Figure 36. — Cyprids of South Carolina: Chelonibia patula (A); 
 Chthamalus fragilis (B); Octolasmis muelleri (C); Balanus trigonus 
 (D); Balanus amphitrite reared at 30°C (E); B. amphitrite reared at 
 20°C (F). Scale = 0.1 mm. 
 
 Cyprid of other species have not been observed di- 
 rectly. A more thorough study of pigmentation, size 
 variations, and fine carapace detail may eventually 
 result in methods to identify all cyprids. 
 
 DISCUSSION 
 
 Based on the proposed classification of the Balano- 
 morpha (Newman and Ross 1976), larvae from at least 
 one species of each balanomorph superfamily were ex- 
 amined: Chthamaloida, Chthamalus; Coronulaidea, 
 Chelonibia; and Balanoidea, Conopea and Balanus. Two 
 lepadomorph genera, Octolasmis and Lepas, were also 
 studied. As the number of cirriped larval descriptions in- 
 creases, it may be possible to correlate many larval 
 characteristics with adult taxonomy. At present, 
 information is too sparse to undertake a detailed study, 
 but certain general patterns are evident. 
 
 As observed by many previous authors, the trilobed 
 naupliar lb is specific to the superfamilies Coronulaidea 
 and Balanoidea. These groups were originally combined 
 under the family Balanidea (Pilsbry 1916) and the use of 
 the term "balanid nauplii" in this study refers to larvae 
 from either superfamily. A unilobed lb occurs in larvae 
 from the remaining barnacle groups — the balanomorph 
 superfamily, Chthamaloida, and all known lepa- 
 domorphs and verrucomorphs. Further subdivisions of lb 
 types may be possible as more larvae are described. For 
 example, Lepas and Pollicipes larvae (Table 2) have a 
 broad flat-edge lb while chthamalids have a tapered 
 tongue-shaped lb. 
 
 Five of the North Inlet species studied (Fig. 33) are 
 part of the Balanus amphitrite complex. Within this 
 complex of closely reared species or subspecies it is pos- 
 sible to derive two natural groupings and three sub- 
 groups (Henry and McLaughlin 1975). Based on statis- 
 tical analysis of adult characteristics, B. amphitrite, B. 
 eburneus, B. improvisus, and B. subalbidus were placed 
 together in the "Amphitrite group." Henry and 
 McLaughlin considered B. amphitrite and B. improvisus 
 least similar within this group with B. subalbidus and B. 
 eburneus intermediate between them. A similar pattern 
 exists for the nauplii of these species. Balanus eburneus 
 and B. improvisus larvae are difficult to distinguish 
 while B. subalbidus and B. amphitrite nauplii are simi- 
 lar but relatively distinct from the first species pair. The 
 fifth member of the complex found in North Inlet, B. 
 venustus, was placed in a separate subgroup by Henry 
 and McLaughlin. Larvae of this species, with propor- 
 tionally long caudal spine, lateral spines, and dorsal 
 spines, are quite distinct from other larvae of the com- 
 plex, thus supporting the grouping of adults. 
 
 Balanus venustus nauplii more closely resemble those 
 of Conopea galeata during early stages, but unlike C. 
 galeata, lateral and dorsal carapace spines become 
 progressively smaller at each molt and by stage VI are es- 
 sentially lost. The particularly large dorsal spine of C. 
 galeata larvae is unique for presently described balanid 
 larvae; however, the long AP and DTS, large fh, and 
 well -developed abdominal spines are evident in other lar- 
 
 36 
 
vae of the subfamily Archaeobalaninae (Acasta, 
 Chirona, Eliminius, Solidobalanus — Table 2). 
 
 The coronulid Chelonibia was long considered a 
 primative balanid but has recently been reclassified 
 (Newman and Ross 1976). Although most adults of this 
 group are extremely specialized obligatory commensals 
 (Ross and Newman 1967), C. patula will settle on both 
 crustaceans and shells; its larvae may be typical of the 
 genus but perhaps, like the adult, are a less specialized 
 form. The first and second stage nauplii of C. testu- 
 dinaria, the only other larvae of the genus described, are 
 quite similar to C. patula larvae (Pillai 1958). The sig- 
 nificance of the distinctly pigmented gut region of C. 
 patula larvae is unknown. If this represents yolk cells, C. 
 patula may be evolving a lecithotrophic mode of develop- 
 ment. The bulky body with highly arched carapace is 
 similar to the form of lecithotrophic Scalpellum scal- 
 pellum larvae. 
 
 Features other than the large globular body closely re- 
 semble those of Balanoidea larvae. Setation and setal 
 types are typical; AP spination is similar, but additional 
 spines rarely seen in Balanus are present. This feature 
 also occurs in the coronuloid Tetraclita karandei 
 (Karande 1974b). Of particular note is the retention of 
 SPSS Anl terminal setal pattern in all naupliar stages. 
 Antennular setation tends to be extremely conservative 
 in cirriped nauplii and this variation makes C. patula 
 larvae unique for balanomorphs. 
 
 Chthamalid larvae differ in many aspects from coronu- 
 loid and balanoid larvae and perhaps more closely re- 
 semble lepadomorph larvae. All chthamalid larvae have 
 hispid and feathery setae and a unilobed lb. At least 16 
 setae are present on the An2 endopod of stage VI nauplii 
 of all chthamalid and most lepadomorph larvae, but no 
 more than 14 setae occur in balanid larvae (Table 17). 
 Chthamalus fragilis nauplii, like other described larvae 
 
 Table 17. — Setal counts for the antennae of 
 stage VI nauplii of some barnacle species. "F" 
 indicates feathered setae are present. 
 
 
 Number of setae 
 
 Species 
 
 exopod 
 
 endopod 
 
 Coronulaidea 
 
 
 
 Chelonibia patula 
 
 12 
 
 14 
 
 Tetraclita purascens 
 
 10 
 
 14 
 
 Balanoidea 
 
 
 
 Eliminius modestus 
 
 12 
 
 14 
 
 Conopea galeata 
 
 11 
 
 14 
 
 Balanus balanus 
 
 9 
 
 11 
 
 Balanus eburneus 
 
 12 
 
 14 
 
 Chthamaloidea 
 
 
 
 Chthamalus fragilis 
 
 12 
 
 18F 
 
 C. stellatus 
 
 12 
 
 18F 
 
 C. aestuarii 
 
 12 
 
 19F 
 
 Octomeris angulosa 
 
 12 
 
 17F 
 
 Chamaesipho columna 
 
 12 
 
 17F 
 
 C. brunnea 
 
 12 
 
 16F 
 
 Other 
 
 
 
 Verruca stroemia 
 
 12 
 
 16F 
 
 Pollicipes polymerus 
 
 12 
 
 16F 
 
 Lepas fascicularis 
 
 12 
 
 16F 
 
 Nauplius Y 
 
 12 
 
 19F 
 
 Octolasmis muelleri 
 
 11 
 
 10 
 
 in the genus (Table 2), lack PS spines and have lost the 
 DTS by stage VI. The nauplii of the pedunculate bar- 
 nacle, Ibla cumingi, bear a striking resemblance to C. 
 fragilis and C. stallatus (Bassindale 1936) larvae, but the 
 sketchy description (Karande 1974c) of Ibla nauplii pre- 
 vents a detailed comparison. 
 
 Octolasmis muelleri and 0. forrestii larvae appear 
 atypical in many aspects. In general appearance the 
 nauplii most closely resemble Lepas larvae and indeed, 
 the poecilasmatid Octolasmis is considered to be closely 
 related to the Lepadae (Newman et al. 1969). As indi- 
 cated in the figures of Lepas fascicularis nauplii (Bain- 
 bridge and Roskell 1966), Lepas, like Octolasmis, has 
 bristled setae on the Anl (a feature presently unique to 
 these two groups). Octolasmis larvae, however, lack AP 
 spination, have a unique tapered lb, exhibit reduced 
 setal numbers on the An2 (Table 17), and have a much 
 reduced Mn. The cs does not develop a posterior border 
 until stage V. None of these features are shared with lar- 
 vae of other barnacle species. The significance or possi- 
 ble advantage of these modifications in Octolasmis lar- 
 vae is unknown. The reduction of the Mn and presence of 
 specialized setal types on the Anl infers a possible 
 modification of the general feeding behavior described 
 for balanid larvae (see Rainbow and Walker 1976). The 
 swimming pattern in Octolasmis nauplii consists of a 
 slow sweeping movement of the appendages as opposed 
 to a much more rapid beat for balanoid nauplii. It ap- 
 pears likely that there are fundamental differences in 
 swimming and feeding behavior. 
 
 Nauplius SC clearly demonstrates the present limited 
 knowledge of cirriped larvae. Although the most com- 
 mon cirriped larval type in offshore plankton samples ex- 
 amined, nauplius SC does not closely resemble any lar- 
 vae of known origin (Table 2). The unilobed lb, fea- 
 thered setae, and An2 setation clearly excludes it from 
 coronuloid and balanoid species. The tapered lb, small 
 size in later stages, and furcal structure run counter to 
 known features of Lepas larvae. The lack of teeth on the 
 lb and absence of hispid setae also make it a doubtful 
 chthamaloid species. Although the size and lb resemble 
 Octolasmis larvae, the short fh and appendages do not. 
 
 Nauplius SC thus appears to originate from one of the 
 numerous lepadomorph or verrucomorph families with 
 unknown larval types. If its larvae are equally predomi- 
 nant at other times of the year, positive identification 
 would be of interest both for larval biology and cirriped 
 species distribution. 
 
 ACKNOWLEDGMENTS 
 
 I wish to acknowledge the Belle W. Baruch Founda- 
 tion and U.S. Environmental Protection Agency (EPA) 
 for their support of this research and particularly note 
 the aid of Winona Vernberg, School of Public Health, 
 University of South Carolina, and Don Miller, EPA. 
 Richard Steele supplied algae used for rearing larvae in 
 Rhode Island. Martha Marcy assisted in rearing and 
 maintenance of barnacle adults and nauplii. William 
 Newman, Scripps Institute of Oceanography, provided 
 
 37 
 
valuable criticism and editorial assistance. Portions of 
 this paper are based on a dissertation presented to the 
 faculty of the Marine Science Program, University of 
 South Carolina, in partial fulfillment for the Doctor of 
 Philosophy Degree. 
 
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 Tokyo, Japan, October 18-19, 1971. William N. Shaw (editor). (18 
 papers, 14 authors.) February 1974, iii + 133 p. For sale by the 
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 Office, Washington, D.C. 20402. 
 
 391. Calanoid copepods of the genera Spinocalanus and Mimocalanus 
 from the central Arctic Ocean, with a review of the Spinocalanidae. By 
 David M. Damkaer. June 1975, x + 88 p., 225 figs., 4 tables. For sale 
 
 by the Superintendent of Documents, U.S. Government Printing Office, 
 Washington, D.C. 20402. 
 
 392. Fishery publications, calendar year 1974: Lists and indexes. By 
 Lee C. Thorson and Mary Ellen Engett. June 1975, iv + 27 p., 1 fig. 
 
 393. Cooperative Gulf of Mexico estuarine inventory and study — Texas: 
 Area description. By Richard A. Diener. September 1975, vi + 129 p., 
 55 figs., 26 tables. 
 
 394. Marine Flora and Fauna of the Northeastern United States. Tar- 
 digracla. Kv Leland W. Pollock. May 1976, iii + 25 p., figs. For sale 
 by. I he Superintendent of Documents, U.S. Government Printing Office, 
 Washington. D.C. 20402. 
 
 395. Report of a colloquium on larval fish mortality studies and their 
 relation to fishery research, January 1975. By John R. Hunter. May 
 1976, iii + 5 p. For sale by the Superintendent of Documents, U.S. 
 Government Printing Office, Washington, D.C. 20402. 
 
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