• synonyms


[ih-kahy-nuh-durm, ek-uh-nuh-]
  1. any marine animal of the invertebrate phylum Echinodermata, having a radiating arrangement of parts and a body wall stiffened by calcareous pieces that may protrude as spines and including the starfishes, sea urchins, sea cucumbers, etc.
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Origin of echinoderm

1825–35; taken as singular of New Latin Echinodermata, neuter plural of echinodermatus < Greek echîn(os) sea urchin + -o- -o- + -dermatos -dermatous
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for echinoderm

Historical Examples

  • It was at first thought that we had before us an echinoderm in the act of transformation.

    Animal Parasites and Messmates

    P. J. Van Beneden

  • He considers the Rotifers to be "the permanent forms of Echinoderm larvæ."

    Marvels of Pond-life

    Henry J. Slack

  • Actinotrocha (fig. 230) undoubtedly resembles more closely Echinoderm larv than the Trochosphere.

  • Tornaria (fig. 229) cannot be definitely united either with the Trochosphere or with the Echinoderm larval type.

  • There are thus indications that in two important points the Echinoderm larv are more primitive than the Pilidium.

British Dictionary definitions for echinoderm


  1. any of the marine invertebrate animals constituting the phylum Echinodermata, characterized by tube feet, a calcite body-covering (test), and a five-part symmetrical body. The group includes the starfish, sea urchins, and sea cucumbers
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Derived Formsechinodermal or echinodermatous, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for echinoderm


1835, from Modern Latin Echinodermata, name of the phylum that includes starfish and sea urchins, from Greek ekhinos "sea urchin," originally "porcupine, hedgehog" (see echidna) + derma (genitive dermatos) "skin" (see derma); so called from its spiky shell.

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Online Etymology Dictionary, © 2010 Douglas Harper

echinoderm in Science


  1. Any of various marine invertebrates of the phylum Echinodermata, having a latticelike internal skeleton composed of calcite and usually a hard, spiny outer covering. The body plans of adult echinoderms show radial symmetry, typically in the pattern of a five-pointed star, while the larvae show bilateral symmetry. Echinoderms probably share a common ancestor with the hemichordates and chordates, and were already quite diversified by the Cambrian Era. They include the starfish, sea urchins, sand dollars, holothurians (sea cucumbers), and crinoids, as well as thousands of extinct forms.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.