Jain Biology ► [01] Biology : Science Of Living Organisms ► 9. Phylum Echinodermata (Spiny Skin):

Posted: 16.09.2009

All the members belonging to this phylum are exclusively marine. Most of them have an endoskeleton of plates of calcium carbonate embedded in the body wall with protruding spines.

Locomotion is by water vascular system; digestive tract is simple and usually complete; circulatory system is radiate, but reduced; respiration is by means of gills, by tube feet etc.; nervous system "has a circular oral nerve ring and radial nerves; sexes are usually separate, alike externally; a few reproduce asexually) by self-division and many generate lost parts. Examples—Starfish, brittle star, sea urchin, sea-cucumber (holothurian).

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