Indian J. Fish., 47(3) : 201-207, Jul.-Aug., 2000

Early development of () pileare and C. () cutaceum (Ranellidae : : ) in the laboratory

P. MUTHIAH* AND K. SAMPATH Department of Zoology, V.O. Chidambaram College, Tuticorin-628 008, India

ABSTRACT Early development of two species of ranellids, Cymatium (Monoplex) pileare and C. (Linatella) cutaceum were studied in the laboratory. Females incubated the egg mass for 12-25 days till fully developed larvae were hatched out through an apical orifice of the egg capsule. The mean length and height of the released larvae of C.(M.) pileare and C.(L.) cutaceum were 252 and 166 pm and 265 and 191pm respectively. The percentage of hatching and larval development was 95.6 and 100 for CAM.)pileare and 93.7 and 94.6 for C.(L.) cutaceum respectively. The larval development inside the egg capsule of these species are discussed.

Introduction cutacea and Cymatium corrugatum. Govan (1995) reported the size of larvae The egg masses of certain species of released by Cymatium spp. This paper ranellids occurring in New Zealand reports on the early development of (Laxton, 1969); Hawaii (Houbrick and larvae from the egg masses, to the Fretter, 1969) and India (Muthiah and juvenile ranellids in the laboratory. Sampath, 1999) were studied earlier. Detailed reports on larval development Material and methods of ranellids are not available. Scheltema (1961) studied the probable veligers of Twenty two C.(M.) pileare, of length cymatiids collected in the range 31.3-93 mm and 17 C.(L.) samples and Bandel (1975) described cutaceum, of length range 48-76 mm the veliger larvae of cymatiids. were collected from rearing cages in an Thangavelu and Muthiah (1983) stud­ experimental pearl culture farm at ied the larval stages of C. cingulatum, Tuticorin (Lat. 8°, 48' N; Long. 78° 11' by rearing the teased out contents of the E). These gastropods were maintained egg capsules. This was not in accor­ separately in FRP tanks of 100 1 dance with normal development taking capacity (size: 75 x 50 x 50* cm). Sand- place in situ the egg capsules. Ramon filtered sea water was used with mild (1991) described the egg mass and aeration. The water was changed daily. development of C. cutaceum, a Mediter­ The were fed with meat of ranean - West-African species Cabestana edible oyster, Crassostrea madrasensis.

* Present address: Central Marine Fisheries Research Institute, 115, N.K. Chetty Street, Tuticorin-628 001, Tamil Nadu, India. P. Muthiuh unci K. Sampnlh 202

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species in the present study is much shorter than other species and this may be attributed to the higher tempera­ ture. The incubation period for C.(L.) cutaceum was 14 clays whereas it took 18 days at 27.2°C for C.(M.) pileare and at 24.8°C, the period extended to 25 days. Govan (1995) reported that the incubation period for C. muricinum, C. ni.cobaricum and C. pileare was 10-2? days. Hatching of C. nicobaricum took place 21 days after spawning (Purtymun, 1974). C. corrugaiurn took 18 days for development at a temperature of 20- 23"C (Ramon, 1991). Similar observa­ tions of decrease in the incubation period with increasing temperature have been made in the oyster drill Otosalpinx cinerea (Ganaros, 1958) and in Eupleura caudata (Mackenzie, 1961). The appearance of the prepodium is considered as a prerequisite for meta­ morphosis (Hadfield, 1978). The pres­ ence of well developed prepodium at a length of 214 pm in C.(M.) pileare and at 239 pm in C.(L.) cutaceum indicated their competence for metamorphosis. The larval length on hatching was 225 pin for C.(M.) pileare and 265 mm for C.(L.) cutaceum. The lengths of hatched out larvae of these ranellids were more close to 280-250 pin as reported by Govan (1995) for Cymatium L.I aquaiiie, C. muricinum, C. nicobaricum and C. pileare.

Discussion It was observed that the larval growth in relation to duration was faster The attainment of brown colour in in C.(L.) cutaceum (length of larvae = the egg masses of ranellids indicate the 115.7178 prn x daysO.304) (Fig. 12) com­ development of the larval shell, as pared with C.(M.) pileare (length of lar­ obse rv eci i n E up I e u r a c a u d a t a vae = 129.8302 pin x days 0.2007) (Fig. (Mackenzie, 1961) and in Cymatlum 13). The surface sculpturing or orna­ comigalum (Ramon, 1991). mentation of protoconchs was similar to the observations of Rarnon (1991) and Govan (1995) for the Cymatium species. P. Muthiah and K. Sampath 206

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Fig. 12. C.(L.) cutaceum Growth of larvae Fig. 13. C.(M.) pileare: Growth of larvae inside inside the egg capsule. the egg capsule. In this study the 'developmental that C.(M.) pileare could drill its prey, period' of 12-15 days and the 'delay eventhough it is usually considered to period' of 30 days are much lower than be a non-boring predatory gastropod the estimated pelagic life of 320 days for while feeding on edible oysters (Muthiah C. nicobaricum and 293 for C. par- et al., 1987) and pearl oysters (Chellam thenopeum (Scheltema, 1971). Probably et al, 1983). with the suitable food and favourable substratum, the 'obligatory develop­ Though large-scale larval mortality mental period' (ODP) (following the occurred, juveniles of C.(M.) pileare up terminology of Scheltema, 1971) will be to a length of 1.5 mm were successfully even much shorter. The growth rate of obtained in the laboratory. Ramon released larvae to juveniles of C.(M.) (1991) attributed absence of suitable pileare ranging from 20.8 um day'1 substratum for the poor survival of (during development inside the egg larvae of C. corrugatum reared for 16 capsule) and 26.3 um day"1 indicates days after their release, similar to that the ODP will be well below 1 Nassarius obsoletus (Scheltema, 1961). month for the larvae of the ranellids, as Govan (1995) stated that due to lack of Govan (1995) envisaged. knowledge on appropriate food required for ranellid larvae, they could not be A bore hole found on the shell of a reared to settlement or even to the dead juvenile (Fig. 10) vouch for the stage of protoconch II. Besides finding cannibalistic behaviour of C.(M.) pileare a suitable substratum, further study is even during juvenile stage, as no other needed to identify ideal food organisms was present that could produce for successful rearing of larvae and the drill hole. It also revealed the fact juvenile ranellids. Early development in two gastropod molluscs 207

Acknowledgments Houbrick, J.R. and V. Fretter 1969. Some aspects of the functional anatomy and We thank Dr. Beu, Institute of biology of Cymatium and Bursa. Proc Geological and Nuclear Sciences, New Malacol. Soc, London, 38 : 415-429. Zealand for identification and valuable Laxton, J.H. 1969. Reproduction in some New suggestions for improvement of the Zealand (Gastropoda: manuscript. We also thank Dr. E. Prosobranchia). Zool. J. Linn. Soc, 48 : Vivekanandan, Senior Scientist, Chennai 237-253. Research Centre of CMFRI for construc­ Mackenzie, C.L. 1961. Growth and reproduc­ tive corrections and the Officer-in- tion of the oyster drill, Eupleura caudata charge, CMFRI, Tuticorin for laboratory in the York river, Virginia. Ecology, 42 : facilities provided. 317-338. Muthiah, P. and K. Sampath 1999. Spawn and References fecundity of Cymatium (Monoplex) pileare and Cymatium (Linatella) cutaceum Bandel, K. 1975. Embryonalgehause (Gastropoda: Prosobranchia), MS. Karibischer Meso- und Neogastropoden (Mollusca). Abh. Akad. Wiss. Lit., Math.- Muthiah, P., D. Sundararajan, G. Srinivasan Naturwiss, Kl. No. 1, 39-44. and N. Vaithinathan 1987. Pest and predators of oysters. In: K.N. Nayar & Chellam, A., T.S. Velayudhan, S. Dharmaraj, S. Mahadevan (Eds.). Oyster Culture : A.C.C. Victor and A.D. Gandhi 1983. A Status and Prospects. Bull. Cent. Mar. note on the predation of pearl oyster Fish. Res. Inst., No. 38, p. 71-74. Pinctada fucata (Gould) by some gastro­ pods. Indian J. Fish., 30 : 337-339. Purtymun, R. 1974. Cymatium egg-laying in a home aquarium. Hawaiian Shell News, Davis, H.C. and R.R. Guillard 1958. Relative 22 : 1. value of ten genera of micro organisms as foods for oyster and clam larvae. Ramon, M. 1991. Spawning and development Fish. Bull, U.S. Fish and Wildlife Ser., characteristics of Cymatium cutaceum 58 : 293-304. and C. corrugatum (Gastropoda: Proso­ branchia) in the laboratory. Ophelia, Fretter, V. and A. Graham 1962. British 33 : 31-43. Prosobranch Molluscs: their Functional Anatomy and Ecology. Ray Society, Lon­ Scheltema, R.S. 1961. Metamorphosis of the don, 755 pp. veliger larvae of Nassarius obsoletus in response to bottom sediment. Biol. Bull., Ganaros, A.E. 1958. On development of early 192 : 92-109. stages of Urosalpinx cinerea Say at constant temperatures and their toler­ Scheltema, R.S. 1971. Larval dispersal as a ance to low temperatures. Biol. Bull., means of genetic exchange between 114 : 188-195. geographically separated populations of shallow-water benthic marine gastro­ Govan, H. 1995. Cymatium muricinum and pods. Biol. Bull., 140 : 284-322. other ranellid gastropods: major preda­ tors of cultured tridacnid clams. 1CLARM. Thangavelu, R. and P. Muthiah 1983. Preda­ tion of oyster Crassostra madrasensis by Tech. Rep., No. 49, 136 pp. gastropod Cymatium cingulatum Hadfield, M.G. 1978. Metamorphosis in ma­ (Lamarck) in the oyster farm at Tuticorin. rine molluscan larvae : an analysis of In: Proc. Symp. Coastal Aquaculture, stimulus and response: In: F.S. Chia and Part 2. E.G. Silas, K. Alagarswami, P.V. M.E. Rice (Eds.), Settlement and Meta­ Rao, K. Rengarajan, K. Nagappan Nayar, morphosis of Marine Invertebrate Lar­ S. Mahadevan and K. Satyanarayana vae, p. 165-175. Elsevier North Holland, Rao (Eds.), Mar. Biol. Assn. India, Amsterdam. Cochin, p. 488-494.