Any of numerous radially symmetrical marine invertebrates of the phylum Echinodermata, which includes the starfishes, sea urchins, and sea cucumbers, having an internal calcareous skeleton and often covered with spines.
[From New Latin Echīnodermata, phylum name : ECHINO- + -dermata, -skinned (from Greek derma, dermat-, skin; see -DERM).]
e·chi′no·dermal, e·chi′no·derma·tous (-dûrmə-təs) adj.
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