The eight classes of molluscs are:
1) Aplacophora: These are small, worm-like molluscs that lack a shell. They live in the deep ocean and feed on organic matter.
2) Bivalves: Bivalves are the largest class of molluscs, with over 20,000 known species. They have two hinged shells that enclose the body. Bivalves include clams, oysters, mussels, and scallops.
3) Cephalopods: Cephalopods are the most intelligent and active of all molluscs. They have a well-developed head with large eyes and a beak. Cephalopods include octopuses, squids, and cuttlefish.
4) Gastropods: Gastropods are the largest class of molluscs after the bivalves. They have a single spiral shell that encloses the body. Gastropods include snails, slugs, and limpets.
5) Monoplacophora: Monoplacophora are a small group of primitive molluscs that have a single, cap-shaped shell. They live in the deep ocean and are rarely seen.
6) Polyplacophora: Polyplacophora are commonly known as chitons. They have a series of eight overlapping plates that cover the body. Polyplacophora live on rocky shores and feed on algae.
7) Scaphopoda: Scaphopoda are tusk shells. They have a long, tubular shell that is open at both ends. Scaphopoda live buried in the sand and feed on organic matter.
8) Solenogastres: Solenogastres are a small group of worm-like molluscs that lack a shell. They live in the deep ocean and feed on organic matter.
Each of these classes of molluscs has its own unique characteristics and adaptations. They are found in a wide variety of habitats, from the deep ocean to the land. Molluscs play an important role in the marine ecosystem, as they are a food source for many other animals.