In this article we will discuss about the structure of Cucumber (Holothuria) with the help of a diagram.1. It is commonly known “cucumber”, is marine and shallow waters.
2. Body elongated, cylindrical, broad in the middle and tapering behind.
3. The mouth and anus (cloaca) are situated at opposite ends one being at anterior and the other at posterior end.
4. Body surface is leathery and bears numerous transverse grooves or wrinkles and is covered with small locomotory tube feets on ventral surface and papillate tube feets on the dorsal.
5. The spines, pedicillariae, branchiae or plates are all absent but small calcareous particles are found embedded in the body-wall.
6. Mouth is bordered by ten oral tentacles.
7. Madreporite is internal and so also the respiratory tree.
8. Sexes are separate, gonads are arranged in a singe tuft and development includes Auncularia larva.