Mollusca

Andaman and Nicobar Islands have a rich molluscan diversity, which Include more than 1000 species from the marine region. Gulf of Mannar and Lakshadweep have 428 and 424 species respectively. 3,370 species of marine molluscs have been reported from India that includes those occurring in coral reef ecosystem as well as other areas. The molluscan diversity studies of Andaman and Nicobar Islands were started in the late 19th century. The literature available shows that the earliest molluscan (Shells) study was on a collection of marine shells made by Smith in 1878.

Subba Rao and Dey (2000) catalogued 1282 species of marine molluscs from these Islands. They occur in different habitats such as mangroves, coral reefs, rocky coasts, sandy beaches, sea grass beds and also at greater depths in the sea.

The phylum Mollusca is typically divided into nine or ten taxonomic classes, of which two are extinct. The gastropods (snails and slugs) include by far the most classified species, accounting for 80% of the total. Cephalopod molluscs such as squid, cuttlefish and octopus are among the most neurologically advanced invertebrates. Either the giant squid or the colossal squid is the largest known species of animal without a backbone.

The phylum Mollusca is very large consisting of thousands of species commonly known as shells. The number of species of molluscs recorded from various parts of the world varies from 80,000 to 1, 50,000 . In India 5070 species of mollusca have been recorded from freshwater (183 species); land (1487 species) as well as from marine habitats (3370 species).