Biology (NTSE/Olympiad)  

4. Diversity In Living Organism

Phylum - Echinodermata

Phylum - Echinodermata :
They are marine, gregarious (live in groups) and free-living animals.
Shape may be star-like, spherical or elongate.
Body surface is covered all over by calcareous spines.
Aristotle’s lantern for mastication.
Their symmetry is radial in adults but bilateral in larvae.
Tube feet for locomotion.
These are unsegmented.
Body cavity is modified into a water-vascular system or ambulacral system with tube like outward extension for locomotion, called tube feet.
Examples : Asterias (Star fish), Echinus (Sea urchin), Holothuria (Sea cucumber), Antedon (Feather star)


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