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Chemoreception in Spider Conch, Lambis Lambis (Mollusca: Gastropoda)

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Sm all er Re s e ar ch Cont r ib utions 111 Chemoreception in spider conch, Lambis lambis (Mollusca: Gastropoda) V. Deepak Samuel & |amila Patterson Samuel, V.D. & J. Patterson. 2001. Chemoreception in spider conch, Lambis lambis (Mollusca: Gastropoda) - Phuket Marine Biological Center Special Publication 25(1,): 111,-11,2. Extracts of sea weed, clam, fish, crab, acid, base and commercial agar were used in chemoreception tests of Lambislambis. This species exhibited a faster response towards extracts of red algae (Hypnea muscifurmis, Hypenea aalentise and Gracilnria corticatn) than towards other extracts. V. Deepak Samuel and I amila P ntterson. Suganthi Deuadason Marine Research lnstitute 44, Beach Road, Tuticorin - 528 001,India. E-mail : s dmar i@m d4.u snl. ne t. in the laboratory. They were starved for 7 days INTRODUCTION before the olfactory tests. A11 the animals Gastropods possess a sensory organ referred measured about 13.5 cm in length. Tests were to as the osphradium. It consists of patches of performed in rectangular tanks containing epithelium located on the posterior margin of filtered sea water. each afferent gill membrane and they function Extracts were made of plants and animals: as chemoreceptors. The osphradium can also red algae Graciloria corticata, Hypnea detect the amount of sediment in the inhalant musciformls and H. aalentine, greer. algae Ulaa current (Barnes 1987). The gastropods receive lactuca, brown algae Sargassum ruightii, the stimuli through the respiratory current. The clams Meretrix meretrix and Donax cuneAtus, time needed for olfactory detection may vary cuttlefish Sepiabreaimana, crab Cancer Sp., and between species. fish Sillago sihama were selected and about 50 Four types of reaction to stimuli have been g were homogenized (1:1; v l*). 10 g of described: positive response where the industrial agar was boiled in 100 ml distilled animals tries to reach the stimulus as fast as water and cooled in a Petri dish. 50% Nitric possible; negative response where the animal acid was prepared using distilled water; turns away from the stimulus; defense sodium chloride, calcium carbonate, response where the animal contracts and try potassium iodide and copper sulphate were to avoid exposure to the stimulus; escape dissolved in distilled wate(, and added at 1:1 response where the animal tries to move away % concentrations. from the stimulus. Two ml organic extracts were dropped on The present study was carried out in Whatman No.1 filter paper and air-dried. The connection with studies on feeding biology of dried filter paper was placed in the center of Lambis lombis, which inhabit shallow areas, the experimental tank. Animals were placed sandy and muddy in nature at depths ranging in each of the 4 corners of the tank and the from 4-1.6 m (Siraimeetan et nL I9BB). time recorded for eversion of proboscis, and the time to reach the stimulant. Change of MATERIALS AND METHODS behaviour was recorded at 30 min intervals. L. lambis were collected at Vellap atti, off The inorganic compounds were dropped near Tuticorin. The animals were kept in tanks of the siphon from a 5 ml filler. Immediate r72 Tropical Marine Mollusc Programme (TMMP) Table 1. Reaction time and response olLambis lambis towards extracts from seaweeds and industrial agar. Time for eversion of Time to reach the Sea weed Activity Response proboscis (min) stimulant (min) Gracilaria corticata 1.42 5.40 very active very positive Hypnea musciformis 1.10 5.12 very active very positive Hypnea aalentiae 1..74 3.45 very active very positive Industrial agar 1.12 3.12 very active very positive Sargassum zoightii 4.35 8.23 sluggish positive Ulaa lactuca 5.20 17.0 sluggish slightly positive response after introduction of stimulant was made from red algae.Ulaalactuca, a green alga recorded. was less preferred. The response was negative RESULTS towards animal crude extracts. This is in Lombis lambis exhibited positive response agreement with Pinn (1990) stating that Lambis towards red algae G. corticata, H. musciflrmis, lambis are vegetarians and feed on special and H. aqlentine. Snails started to search for the kinds of algae. Carbohydrates stimulated area emitting the stimulus (Table 1). The feeding responses in Babylonia zeylonica and proboscis was fully everted and kept moving B. spirata whereas acids and bases induced from side to side. Green and brown algae were escape responses (Raghunathan & less attractive. A negative response was Ayyakkannu 1995). In Lambis lambis, the identified in snails exposed to animal extracts. escape response was distinct with nitric acid The snails moved away after reaching the at 40 and 50% concentrations and pottassium stimuli. A defensive response was obvious iodide, calcium carbonate salts resulted in a when salts were introduced. The snails defensive response. retracted and did not expose the soft body for a while. This defensive response was exhibited REFERENCES towards calcium carbonate, pottassium iodide Barnes,D.R. 1987. Some organs of Gastropods. and sodium chloride. Astrong escape response Invertebrate Zoology. Vth edition, CBS was exhibited towards acid and copper Coliege Publishing. pp 383-384. sulphate. The snails tried to escape with rapid Pinn,Fred. 7990. Sea snails of Pondicherry and vigorous movements. coast - Nehru Science Centre Pondicherry. KohruA.J . 1961,. Chemoreception in gastropod DISCUSSION molluscs. - AnimaI Zoology. I: 29I-308. A stimulus triggers a stereotyped sequence of Raghunathan,C. & K.Ayyakkannu, 1995. behaviour of afixed action pattern (Tinbergen Chemoreception in the Buccinid 1,951). Resolution by chemoreception in Gastropods, Bnbylonia zeylonica and gastropods is potentially greater than by Babylonia spirnta (Neogastropoda: vision (Kohn 1961) allowing them to respond Buccinidae). - Phuket Marine Biological to specific stimulus. This is the reason for the Center Special Publication 15: 799-204. animal to select its food and graze on it. Siraimeetan et nl.I9BB. On the habitat, habits Both plant and animal crude extracts and food of Lnmbis lqmbis and Hemifusus resulted in extension of the proboscis. Stimuli cochlidium- CMFRI Bulletin 42Partl pp. 111- reaching the olfactory organ resulted in fast 176. movements so the snail could reach extracts Tinbergen,N. 195L The study of instinct. of red algae and industrial agar fast. Agar is Londoru Oxford University Press..
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