In this article we will discuss about the structure of Terebra & Terebellum (Shankh) with the help of a diagram.
1. They are called “turret shells” and are marine molluscs.
2. They exhibit torsion and the nervous system is twisted in a figure of 8.
3. In these molluscs the left side has completely atrophied.
4. They have single auricle, nephridium, ospharidium and ctenidium.
5. The foot is operculate and large.
6. Ctenidium is monopectinate and comb-like.
7. Ospharidium is pectinate.
8. Sexes are separate and development through trochophore larva.