In the Indian Ocean more than 160 species of Holothuroid Echinodertns have been recorded, of which 150 species are available in the collection of the Zoological Survey of India. These include about 75 species from the deep Sea and another 70 species from shallow offshore and littoral regions. The remaining species occur exclusively on reef flats of Coral islands i. e. Andamans, Nicbbars, Krusadi and adjacent islands in the Gulf of Mannar, Pirotan island and adjacent Coral beds in the Gulf of Kutch and LaccadiveMinicoy-Mildive groups of islands; these species contribute to the ' Beche-de-mer' or ' trepang' industry.

The geographical and bathymetrical distribution pattern of all the valid species of hoiothuroidea of the Indian Ocean are also presented. An attempt has been made to explain the distribution chiefly in relation to Oceanic currents and bottom topography.