TAXONOMY , BIODIVWESITY , DISTRIBUTION OF GASTROPODS IN INDIA

REGARDING DISTRIBUTION OF DIFFERENT SPECIES OF GASTROPODS IN INDIA

1. KERALA UNIVERSITY OF FISHERIES AND OCEAN STUDIES DEPARTMENT : FISHERIES RESOURCE MANAGEMENT COURSE TITLE : MARINE ECOSYSTEMS , BIODIVERSITY AND CONSERVATION COURSE NO : FRM-503 RM 51 TOPIC : Taxonomy , diversity and distribution of gastropods with special reference to India SUBMITTED BY RAVI KIRAN PAMISETTY FSM-2020-20-07

2. PHYLUM - MOLLUSCA Includes all   snails  and  slugs , clams ,  oysters ,  scallops ,  geoducks ,  mussels Mollusca  is the second-largest  phylum  of  invertebrate  animals after the  arthropoda . Around 85,000  extant   species  of molluscs are recognized . Molluscs are terrestrial or aquatic ( F.W & M.W) A total of 3,271 species of molluscs are distributed along the Indian coast which includes 220 families and 591 genera Molluscs are the largest  marine  phylum, comprising about 23% of all the named marine  organisims They are bilaterally symmetrical and coelomates animals. Body covered with calcareous shell and is unsegmented with distinctive head , muscular foot ,visceral mass Except cephalopods circulatory system is open type.

3. Molluscs are classified into classes based on symmetry , shell , mantle ,gills , nervous system and radula.

4. Class- gastropoda The  gastropods  commonly known as  snails and slugs The class Gastropoda contains a vast total of named species, second only to the  insects  in overall number. they are most highly diversified  class  in the  phylum mollusca , with 65,000 to 80,000  living snail and slug  species .  There are 444 recently  extinct  species of gastropods (extinct since the year 1500), 18 species that are now  extinct in the wild  (but still existing in captivity) and 69 "possibly extinct" species . About 1900 species of gastropods have been reported from India In marine habitats, the  continental slope  and the  continental rise  are home to the highest diversity of marine gastropods. Gastropods are asymmetrical molluscs that underwent torsion.

5. Gastropods are classified mainly into three sub classes 1.Prosobranchia It include the majority of marine snails, among them  conches ,  cones ,  cowries ,  limpets ,  murexes ,  periwinkles ,  volutes  and  whelks 2. Opisthobranchia It includes   sacoglossans ,  anaspidean   sea hares , pelagic  sea angels ,  sea butterflies etc.., 3. Pulmonata It includes snails and slugs   

6. List of commercially exploited gastropods from Indian waters

7. Babylonia spirata (whelk) Mainly found along tamilnadu coast and also in west coast They are mostly carnivorous and scavengers . Shell is thick, smooth with distinctive spiral and conical in shape. The shell coloration and pattern of colour design is variable from plain brown to white with brown or orange spots. The meat is edible and the shell is used in the shell craft industries.

8. Tectus niloticus This marine species is widespread in the  Indo-Pacific region , mainly found in the Andaman and Nicobar Islands . live in shallow areas on intertidal reef flats, along the reef crest or on reef slopes feed on very small plants and filamentous algae grazed on coral and rocks . conical in shape ,Outer surface of the shell is white with many reddish-brown longitudinal bands

9. Chanks ( Turbinella pyrum ) Turbinella pyrum ,  common names  the chank shell, sacred chank or chank, also known as the  divine conch Major chank resources occur in the Gulf of Manner, particularly along the Ramanathapuram – Tirunelveli coast. Other areas are Tanjavur, South Arcot and Chingelpet in Tamil Nadu, Trivandrum coast in Kerala, the Gulf of Kutch in Gujarat and the Andaman's.   The shell is huge, thick, pear-shaped and coated with a brownish horny periostracum

10. Lambis lambis (   spider conch) These lives in  mangrove  areas, as well as  reef  flats and coral-rubble bottoms in shallow water Lambis lambis  is known to be  herbivorous , feeding on fine  red algae . The five-fingered chank is large, thick and heavy with a slightly high and pointed spire . Dorsal surface of body is rough, with uneven spiral cords and 2 or 3 spiral rows of blunt tubercles, forming large knobs on the shoulder.   Mainly distributed along east coast

11. Agaronia gibbosa It is mostly found on southeren parts of east and west coast. Mostly found on Coastal, sandy bottom. Colour pale yellowish brown with a prominent yellow band at the base, mottled with black spots,Sometimes whitish with zig zag transspiral brownish bands, spire and column yellowish white, aperture bluish white .

12. Cypraea tigris Its mainly found along east coast and Lakshadweep island. Carnivorous, the adult tiger cowrie eats  coral  and various  invertebrates , while juveniles eat  algae . Roughly egg-shaped and dextral, the glossy  shell  is large and heavy for a cowry.  The ventral side is white or whitish, and the  shell opening  is lined with tooth-like serrations.

13. Chicoreus virgineus This species occurs in intertidal regions from the  Red Sea  to the  Bay of Bengal . Shell moderately large in size; fusiform; spire acute; body whorl large and inflated colour pale brown with a slight pinkish band on middle of body whorl; aperture white, margin of aperture pinkish white.

14. Umbonium vestiarium ( button tops) They can be found on  eulittoral   sand ,found mainly in indo- pacific regions , in india along east coast The solid, rounded shells are up to 2 cm wide and are more flattened and show a glossy, highly variable and colourfully patterned exterior .

15. Conus glaucus (   glaucous cone) T hese snails are  predatory  and  venomous . They are capable of "stinging" humans The color of the shell is bluish ash or very light chocolate, with usually a lighter narrow central band, and numerous short chocolate lines in revolving series . It is mostly found on southeren parts of east and west coast.

16. IUCN RED LIST OF GASTROPODS TOTAL number of gastropod species under IUCN red list = 7326  EX - Extinct =267  EW - Extinct in the Wild =14  CR - Critically Endangered (includes CR(PE) and CR(PEW ))=604 EN  - Endangered =518 VU  - Vulnerable=975  LR/cd - Lower Risk/conservation dependent = 0  NT - Near Threatened (includes LR/ nt  - Lower Risk/near threatened )=637  DD - Data Deficient = 1648  LC - Least Concern (includes LR/ lc  - Lower Risk/least concern = 2663

17. species of molluscs have been listed in the Indian Wildlife (protection) Act, 1972, amended in 2001

18. THREATS Housing and urbanization Mining and quarrying. Tourism and recreational areas. Soil erosion and sedimentation. Global climatic change Habitat destruction and fragementation pollution

19. REFERENCES Mohamed, K S (2006) Molluscan Fisheries. In: Handbook of Fisheries and Aquaculture. Ayyappan, S,(ed.) Indian Council of Agricultural Research, New Delhi, pp. 116-134 . Narasimham , K.A., V. Kripa and K. Balan (1993). Molluscan shellfish resources of India An overview. Indian J. Fish. 40(1&2): 112-124. K. Sunil Mohamed and V. Venkatesan MARINE MOLLUSCAN DIVERSITY IN INDIA - EXPLOITATION, CONSERVATION Appukuttan , K.K. 1996. Marine molluscs and their conservation. In Marine BiodiversityConservation and Management. Central Marine Fisheries Institute, Cochin, eds. N.G.Menon and C.S.G. Pillai.