Distribution:-They are found in all seas except polar. They are commonly found in Europe, pacific Coast, New England Coast and Indian ocean..
Habit and Habitat :- Dentalium is marine and found in the sand at great depth. They feed on minute organisms such as Foraminifera and diatoms.
1) Dentalium is commonly known as tusk shell.
2) Body is bilaterally symmetrical and enclosed in a tubular shell open at both ends.
3) Mantle Folds are fused ventrally to form a tube enclosing the body.
4) Well developed radula is present.
5) Anus lies behind the base of the foot.
6) Gills are absent.
7) Eyes absent. Oocysts present.
8) Sexes are separate
9) Development includes veliger larva.
Sheel of Dentalium has ornamental value, the shells are collected on strings and are used as necklaces.
Distribution:- Pecten is cosmopolitan in distribution. It is commonly found in India, and the U.S.A.
Habit and Habitat: – Pecten is marine and free swimming. It is commonly found in India, and U.S.A..
1) Pecten is commonly known as scallops.
2) The shell is beautifully ribbed by radiating lines.
3) Foot is very much reduced.
4) Two large and crescentic gills are present.
5) A large number of stalked eyes are present at regular intervals along the edges of the mantle.
6) Hermaphrodite ovary is pink and testis is cream coloured.
7) After removing the shell are seen large adductor muscles, alimentary canal, gills, ovary, testis , kidneys and many other structures.
Its muscles are consumed by humans in many parts of the world.