Definition of "echinoderm" [e•chin•o•derm]

• 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. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The echinoderm was the first to latch on, gradually growing as it sat on the shell, but sometime later a bryozoan larvae also took up residence there."
• "Agence France-Presse/Getty Images The Great Barrier Reef provides a home for 5,000 to 8,000 species of mollusk and 800 species of echinoderm a phylum that includes starfish and sea urchins."
• "The variety of aquatic wildlife reads like an open casting call for Finding Nemo: Over 1,500 species of fish, 5,000-8,000 species of mollusks, 30 species of whales and dolphins, 600 species of echinoderm such as starfish, 17 varieties of sea snakes, and 6 species of marine turtles which are listed as threatened."