1. Class Caudofoveata

1.They are wormlike molluscs.

2. They have cylindrical, shell-less body and scale like, calcareous spicules.

3. They lack eyes, tentacles, statocysts. crystalline style, foot, and nephridia.

4. They are deep-water, marine burrowers.

Examples: Chaetoderma

2. Class Aplacophora

1.They lack shell, mantle, and foot.

2. They are also wormlike

3. Head is poorly developed

4. They are burrowing molluscs They are marine.

Example: Neomenia.

3. Class Polyplacophora

1. They are elongated and dorsoventrally flattened.

2. Head is reduced in size.

3. Shell consisting of eight dorsal plates.

4. They are marine, on rocky intertidal substrates.

Example: Chiton.

4. Class Monoplacophora

1. They have single arched shell.

2. Their foot broad and flat.

3. They are marine.

Example: zeopilina.

 5. Class Seaphopoda

1.Body enclosed in a tubular shell. It is open at both ends.

2.Tentacles are used for deposit feeding.

3.They have no head.

4. They are marine.

Example: Dentalium.

6. Class Bivalvia

1. Body enclosed in a shell consisting of two valves. Valves are hinged

2. They have no head or radula.

3. They have wedge-shaped foot.

4. They are marine and freshwater.

Eample: Anodonta, Mytilus, Venus

7. Class Gastropoda

1. Shell is coiled.



2. Their body symmetry distorted by torsion.

3. Some monoecious species.

4. They are marine, freshwater and terrestrial.

Example: Nerita, Helix

8. Class Cephalopoda

1.  Foot modified into a circle of tentacles and a siphou.

2. Shell is reduced or absent.

3. Head is in line with the elongated visceral Mass.

4. They are marine.

Example: Octopus, Loligo, Sepia, Nautilus.



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