Complete larval development of the spider crab Eiamenopsis demeloi

(Kemp) was studied from larvae hatched and reared from an ovigerous crab

in the laboratory. At Z6-Z8°C temperature and 17-20 ppt salinity, three zoeel

stages were observed, followed by a first stage crab. A megalopa stage

was not present. Morphological features of these larvae are compared with

the other species of the family and the important characters that differ

from those of other zoeae are: Zaeee with very long mid-dorsal and rostral

spines and coxal endite of 2nd maxilla with 2 setas

Kakati, V S

CMFRI Digital Repository

MAHASAGAR Vol.Z" No.4 (December), 1988, pp.219-227 LARVAL DEVELOPMENT OF THE INDIAN SPIDER CRAB ELAMENOPSIS DEMELOI (KEMP) (BRACHYURA, HYMENOSOMATIDAE) IN THE LABORATORY V.S. KAKATI Karwar Research Centre of Central Marine Fisheries Research Institute Karwar 581301 ABSTRACT Complete larval development of the spider crab Eiamenopsis demeloi (Kemp) was studied from larvae hatched and reared from an ovigerous crab in the laboratory. At Z6-Z8°C temperature and 17-20 ppt salinity, three zoeel stages were observed, followed by a first stage crab. A megalopa stage was not present. Morphological features of these larvae are compared with the other species of the family and the important characters that differ from those of other zoeae are: Zaeee with very long mid-dorsal and rostral spines and coxal endite of 2nd maxilla with 2 setas. Key-words: Larval development, spider crab larvae, Elamenopsis demeloi (Kemp), Brachyura. INTRODUCTION Aikawa (1929) was the first to work on the larva e of Hymenosomatidae, the well known small spider crabs from Indo-Pacific region. Aikawa obtained first stage zoeae from ovigerous females respectively of Halicarcinus messor, Trigonoplax unquiformis and Halicarcinus septentrionalis. Sub-sequently, zoeae of the other hymenosomatids have been figured or des-cribed by various workers, viz. Elamena mathaei by Gurney (1938) and AI-Kholy (1959); Hymenosoma orbiculare by Broakhuysen ( 1955); E. sindensis by Prasad & Tampi (1957); Halicarcinus cooki by Melrose ( 1975); H. planatus by Boschi, Scelzo and Goldstain (1969); E. cristatipes by Hashrni (1970); Amarinus (Halicarcinus) paralacustris and Amarinus laevis (Halicarcinus australis) by Lucas ( 1971 ); H. orientalis and H. messor by Mur<loka (1977) and Trigonoplax unguiformis by Fukuda (1981). Wear and Fielde; (1985) have desc ribed the zoea stages I, II and III of New Zealand species reared from laboratory hatched eggs of Neohymenicus pubescens, Elamena longi-rostris, E. momona and E. producta. In the same publication, these authors have descr ibed the first stage zoeae of Halicarcinus cooki, H. innominatus, H. whitei, H. varius, H. planatus and Hymenosoma depressum from labo-ratory hatched eg gs and in so me cases the subsequent stages were described from the zoeae collected in plankton or reared from the planktonic larvae. Lucas (1980) , Rice (1980) and Wear and Fielder (1985) in their studies have reviewed the larval works of Hymenosomatidae and described the dlagAO_stic characters of the larvae . 220 KAKATI In the present study, Elamenopsis demeloi (Kemp), one of the species of the spider crabs of the family Hymenosomatidae from India, was reared in the laboratory and is described. MA TERIAL AND METHODS Larvae were obtained from an ovigerous crab, Elamenopsis demeloi (Kemp), collected from the Kali estuary, Karwar, along the west coast of India (Lat. 14°18'N and Long. 74°97'E). This species was observed to be available abundantly near the Kali river mouth where a variable sa linity is encountered. After the co llection the crab was maintained in water of 17 ppt salinity until the larvae hatched . During the experiment salin ity f luctuated between 17 and 20 ppt and temperature between 26 and 28°C. Othe r ovigerous females collected subsequently a lso released healthy larvae leading to successful rearings. The method of rearing the larvae is the same as described by Kakati (1 977). RESUL TS AND DISCUSSION The larvae passed through three 20eal stages. A pre zoea l stage was not observed and none of the third stage zoeae passed through megalopa stage, instead, they moulted directly into first stage crabs . The zoeae were voracious feeders on Artemia nauplii and were always active, covering the entire space of rearing medium . The zoea e reached rirst stage crab within a minimum period of nine dais. Survival rate from first zoeae to first stage c rabs was fifty percent. First zoea (F ig . l ) Rastral spine lenglh (RSL) Dorsal spine length (DSL) Cerapace length (CL) Duralion of the stage (DS) = 2.01 mm. = 1.35 mm. ::; 0.63 mm., and 3 days. Carapace w ith ve ry long rostral and dorsal spines, dorsa l spine being sho rter than rostral, tips of both these spines directed in opposite directions, minute spinules present on the surface of rostral spine , eyes sessile, telson quadrangular fFlg.1a & i). Antennule (Fig .1b) : Uniramous wilh 1 small seta and 2 unequal long aesthetascs. Antenna (F ig.1c): Pointed, with a termina l spine, sp ine smooth and almost as long as lobe. Mandible (Fig .1d) : With well developed mola r and incisor processes but withoul pa lp . Maril/ule (Fig.1e) : Coxa l end ite with 5 and basal wilh 4 selae, patp 2-segmented, and long distal segment with 4 setae in two sets of 2 each and the short proximal with 1 seta. Marilla (Fig. l !) : Coxal end ite with 2 selae and slightly bilobed basal with 8, palp bilobed, with 2 setae on proximal lobe and 2.1 on distal, scaphognathite with 3 marginal plumose selae distally Bnd a broad pointed posterior end w ith fine hairs . First marilliped (Fig.1g): Basipod with 10 setae, endopod 5-segmen ted, long, with 3, 2, 1, 2 and 5 setae distalwards, unseg-mented exopod with 4 nata tory setae. Second marilliped (Fig .l h): Basipod 1, . LARVAL DEVELOPIV£NT IT ELAMENOPSIS DEMELO] (KEWP) 221 1 ~1 · ",," 1 b,c,e,f ~d,g.h >-c< I h ,; , !( _ .. " Fig .1. First zoea. (a) Lateral view of zoea; (b) antennule; (c) antenna; (d) mandible; (e) maxillule; (f) maxilla; (g) fist maxilliped; (h) second rnaxilliped; 0) abdomen. with 3 setae, 3-segmented endopod with 1, 1 and 2+4 se tae distal wards, exopod as in first maxilliped. Abdomen (Fig.1il: Five-segmented, segments without dorsal se tae , $8cond segment with posteriorly situated lateral protuberances. Telson (Fig.1i) : Quadrangular, wit~ slightly c urved long c ornua, a small spine near the base of each cornua, te lson process formul a 3.+3, t.he outer process smooth while the inner ones plumose . Chromatophores: Brownish-red chromatophores the dorsal and rostral spines, on teison, mandibles, and second rnaxillipeds, first abdominal segment, on the carapace (Fig.1a). Second zoea (Fig .2). as illustra ted; along labrum, basis of first below the eyestalks RSL = 3.82 mm, OSL = 2.90 mm, CL = 1.4 mm and Os. = 3-4 days . 222 r 0-' nun '.f ~ I b-d I I----,i 9.1 'h' H a KAKATI Fig.2. Second zoea. (e) Lateral v iew of zoe a; (b) antennul e; (c) antenna; (d) mandible; (e) maxillule; (f) maxilla; (g) first maxilliped; (h) second maxilliped; (j) third maxilliped bud. Ventral margin of carapace with 2 setae and eyes sta lked- (Fig.2a). Antennule (Fig.2b): Aesthetascs increased in numb e r from 2 to 4 but was devoid of seta. Antenna (F ig.2c): Terminal spinous portion eccentri ca lly placed. Mandible (Fig.2d) : Increased in size and with strong mo lar surface. Maxillule (F ig.2e) : Coxal endite with 5 setae and basal w ith 6, a plumose seta added distally on outer margin. Maxilla (Fig.2f): Except for increase in number of marginal pfumose setae of scaphognanthite to 9 (6+3) , no other change. First and second maxillipeds (F igs.2g and h): Natatory setae increased to 7, no other change . Oth~r appendages: Third maxilliped (F ig. 2i) biramous. First pereiopod chelate, others as uniramous buds. Abdomen and tel son increased in size and length. LARVAL DEVELOPMENT Of ELAMENOPSIS DEMELOI (KEMP) 223 Fig.3. Third zoea . (a) Lateral view 01 zoea; (b) antennul e ; (c) antenna; (d) maxillule; (e) maxilla; (I) lirst maxilliped; (g) second maxilliped; (h) pereiopod buds. Third zoe a (F ig.3). RSL = 3.30 mm, OSL = 1.40 mm; CL = 1.50 mm and OS = 3-4 days. Ventra l margin of carapace with 3 setae (Fig .3a). Antennule (Fig.3b): Base swo ll e n, with 4 aesthetascs . Antenna (Fig.3c) : Termin al spinous portion now sh ifted subterminally. Maxillule (F ig.3d): Coxa l endite with 5 setae and basal with 7, no ot he r structural change . Maxilla (F ig.3e) : Except for in-crease in number of marginal plumose setae of scaphognathite to 13 (8+5), no other change. First and Second maxillipeds (F igs. I & g): Exopod 2-seg-mented with 8 and 9 natatory setae respective ly on first and second maxilli-peds. Other appendages (F ig.3h): Third ma xilliped and pereiopods 1-5 fairly we ll developed and e longated. 224 KAKATI The third stage zoea moulted directly to first stage c rab. Zoeae of only a si ngle spec ies Elamenopsis lineata A. Milne Edwa rds described by Lucas (1980) have e longated dorsa l and rostral spines like the ones in the present spec ies . Amarinus laevis (H. australis ) (Lucas, 1971) a nd H. orbiculare (Broekhuysen, 1955) have moderately large carapacial spines, bu t are clearly sm a ller than in E. demeloi. The lengthy rost ral and dorsal carapaciai sp ines of the present species a re rem in iscent of the carapacial spines of porcel1anid larvae. The present larva e s t and apart from the la rvae of other species of Hym enosomatidae in gene ral and differ from the above mentione d . latter species in par ticu lar in the sense tha t the rostra l spine in the present larvae has minute spinul es th roughout the e ntire length . The carapace spines appear' t o be an environmental adaptation, s ince these spines help the larva in floata tion and orientation in the turbulent estuarine waters. In th e re aring bow ls, these larvae a lways swam with the ir long carapaciai sp ines oriented horizonta lly to the substratum. The carapaciai spines in the present spec ies increased in lengt h in the second stage zoeae, but decreased in third s tage. These, li ke many ot her hymeno-somat id larvae, neither curl up into balls nor remain near the substratum. The first stage crabs a re thigmotactic in behavio ur and cling to each other thereby forming a ball. Most of the hymenosomatid zoeae have lateral protuberances on second abdom inal segment. A pai r of protuberances was found in the posterior half of the dorsa-lateral portion of the second abdominal segment in E. demeloi, H. or ienta lis and H. messor. However, the third abdominal seg-ment is devoid of any such protub era nces. The fi rst ab do min al segment of H. messor has a mid-dorsal plumose seta wh ich is lack ing in E. demeloi as well as in other species of the family. The abdomen in most af the zoeae has a lobe- lik e projection on the ventral surface of fifth segment. But this projec tion was not observed in E. demeloi. Pleopods or pl eopod buds are ab-sent ·in all the three zoeal stages, thus confor min g to the pattern of life history of the famil y as a whole. The absence of ple opods in any species of the fa mil y can be readi ly attrib uted to the absence of megalopa stage where the function of pleopods is for locomotion. In bot h H. messor and E. demeloi the first stage zoeae possess three se t ae on scaph9gnathite a nd the se t?_tion of endopod of first ma xiUiped is 3,2, 1; 2 and 5 tor both" the species. The" major · difference h om other hymenosomatid zaeae is exhibi ted in number of setae on coxa l endite of maxilla: E. demeloi and E. lineata have 2 setae instead of a single seta hitherto described for the other zoeae of the family. Moreover, number of coxa l setae o f maxillule in E. demeloi is 5 (4+ 1) as against 4 0+1) of the other species. Most spec ies of Brachyura posse~s successively 4, 6, 8, 10, ... natatory setae of exopods of maxillipeds from first stage onwards by a n add iti on of 2 se t.ae in each subsequent stage. This pattern is no t followed in the zoeae of Hym enosom a tidae , in which it is generally represented by 4, 7 and LARVAL DEVELOPMENT OF ELAMENOPSlS DEMELO! (KEMP) 225 8/9 natatory setae in first, second and thirrj stage zoeae respectively. The exopod of first maxilliped is not a 2-segmented appendage in the first two zoeal stages, but in third stage it is clearly 2-:segmented. The exopod of second maxilliped is unsegmented in first stage zoea but 2-segmented in later zoeal stages in E. demeloi. Thus, the segmentation pat-tern of maxillipeds differs among the species described. As already suggested by Lucas (1971), the presence of primary chromatophor'es in both the maxilli-peds is not a good diagnostic feature of the family since other brachyuran families also do possess these (Aikawa, 1937). A small spine is present near the base of each tel son cornua on lateral margin in E. demeloi. Similar spines have been observed in H. rostratus and A. paralacustris but were absent in H. orientalis and H. messor. Lucas (1980) has described the larval characters of the family Hymeno-somatidae based on Wear (1967) and Lucas (1971) as"telson elongate trape-zoidal, wider anteriorly; telson-fork short and straight, with three pairs of close-set spines; 2nd maxillae with single coxal and basal endites, coxal endlte vestigial, with a single seta or, less commonly~ with two setay; antennae simple, varying from inconspicuous blunt lobes to conspi-cuous pointed lobes, pointed form with a fine basal hair or terminal spine which tends to be eccentric; abdomen of 5 segments with no traces of pleopods; with three zoeal stages and without pre-zoeal and megalopa stages. The distinctive telson and tel son fork of hymenosomatid larvae are the most useful characters for identifying these larvae in plankfon samples. There is much variation in the development of carapace spines within this family. Lucas (1980) states that as a rule the hymenosomatid species occurring in brackish water have greater development of the larval cara-pacial spines than do the m.arine species. This statement holds good in case of E. demeloi which is also an estuarine species. Based on the larval characters of E. lineata described by Lucas (1980) and E. demeloi described in the present study, the two important zoeal characters of the genus found are: 1. Zoeae wi th very long mid-dorsal and rostral spines, two and three times the carapace length, respectively, 2. Presence of two setae (not one) on the coxal endite of the 2nd maxilla. The absence of a r:negalopa stage in the present larval development and in those of the other species hitherto described points to the fact that three zoeal stages may be taken into consideration as a general diagnostic feature of the family. ACKNOWLEDGEMENTS The authors are indebted to Prof. V.B. Nadkarni and Dr. K.N. Sankolli, Department of Zoology, Karnatak University for guidance and encourage-ment, and to Dr. J.5. Lucas, Australia, for' confirming the identification 226 KAKATI of the species based on sketches sent to him . This work was supported by funds from the C.s.I.R., India. REFERENC ES Aikawa, H., 1929. On the larval forms of some brachyura. Records of Oceanographic Works in Japan, 2 : 17-55. Aikawa , H., 1933. indeterminable 5: 124-254. On larval forms of some brachyura. Pape r II. A note on zoeas. Records of Oceanographic Works in Japan, Aikawa, H., 1937. Further notes on brachyuran larvae. Records of Oceano-graphic Works in Japan, 9 : 87-162. AI-Kholy, A.A., 1959. Larval stages of four brachyuran Crustacea (from the Red Sea) . Publications of Marine Biological Station, At Ghardaqua, 10: 239- 246. Boschi, E.E ., M.A. scelzo and B. Goldstein, 1969. Desarrollo larval de I c~ntrejo , Halicarcinus planatus (Fabricius) (Crustacea, Oecapoda, Hymenosomidae), en Ie laboratoria, con observaciones sabre la distri-bucion de la especie . Bulletin of Marine Science, 19 : 224-242 . Broekyhusen, G.J., 1955. The breeding and growth of Hymenosoma o'rbiculere Desmarest (Crustacea, Brachyura). Annals of South African Museum, 41: 313-343. Fukuda, Y., 1981. Larval development of Trigonoplar unguiformis (De Haan) (Crustacea, Brachyura) reared in the laboratory, Zoological Magazine, 90: 164-173. Gurney, R. , 1938. Notes on some decapod crustacea from the Red Sea, VI-VIII. Proceedings of the :Jological Society of London, 108(B): 79-84. Hashmi, ~s., 1970. The larvae of Elamena (Hymenosomidae) and Pinnotheras (Pinnotheridae) hatched in the laboratory (Decapod a , Crustacea) Pakistan Journal of Science and Industrial Research, 12: 279-285. Kakati, V.S., 1977. Larval development of the crab, Menippe rumphii (F abri-cius) as observed in the laboratory (Crustacea, Brachyura) . Proceedings of the Symposium on Warm \Vater Zooplankton, Special Publication, UNEsCO/NIO: 634- 641. Lucas, J.s., 1971. The larval stages of Australian species of Halicarcinus (Crustacea, Brachyura, Hymenosomatidae) I. Morphology. Bulletin of Ma-rine Science, 21: 471-490. Lucas, J.S., 1980. Spider crabs of the family Hymenosomatidae (Crustacea, Brachyura) with particular reference to Australian species: Systematics and Biology. Records of the Australian Museum, 33: 148-247. Melrose, M.J., 1975. The marine fauna of the New Zealand: Family Hy-menosomatidae (Crustacea, Oecapoda, Brachyura). Memoirs of New Zea-land Oceanographic Institute, 34: 1-123. LARVAL DEVELOPMENT OF ELAMENOPSlS DEMELOl (KEMP) 227 Muraoka, K., 1977. The larval stages of Halicarcinus orientalis Sakai and Rhynchoplex messor Stimpson reared in the laboratory. Zoological Maga-zine, 86: 94-99. Prasad, R.R. and P.R.S. Tamp i, 1957. Notes on some decapod larvae. Journal of Zoologica l Society of India, 9: 22- 39. Rice, A.H., 1980. Crab ZoeaI morphology and its bearing on the classifi-cation of the Brachyura. Transactions of the Zoological Society of London, 35: 271-424. Wear, R.G. and D.R. Fielder, 1985. The marine fauna of New Zealand: Larvae of the Brachyura (Crustacea, Decapoda). New Zealand Oceano-graphic Institute, Memoir, 92 . 

Larval development of the Indian spider crab Elamenopsis demeloi (Kemp) (Brachyura, Hymenosomatidae) in the laboratory

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Larval development of the Indian spider crab Elamenopsis demeloi (Kemp) (Brachyura, Hymenosomatidae) in the laboratory

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