EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > ANIMALS/INVERTEBRATES > ECHINODERMS
The phylum Echinoderms is a wholly marine group whose members include
the familiar starfish and sea urchins often found on the shore. Some of
their particular features are their five-sided adult symmetry, their
endoskeleton which consists of many small crystals of calcium carbonate
and tube feet, which are outward manifestations of their water vascular
Burn, David M. Animal World. 1980. Octopus Books Ltd. London.