echinoderm

[ ih-kahy-nuh-durm, ek-uh-nuh- ]

noun

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.

echinoderm

/ ɪˈkaɪnəʊˌdɜːm /

noun

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

echinoderm

/ ĭ-kī′nə-dûrm′ /

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.

Derived Forms

• eˌchinoˈdermal, adjective

Word History and Origins

Origin of echinoderm¹

1825–35; taken as singular of New Latin Echinodermata, neuter plural of echinodermatus < Greek echîn ( os ) sea urchin + -o- -o- + -dermatos -dermatous

Example Sentences

However, scientists have found it difficult to determine when brittle stars, a gangly group of echinoderms, started reproducing this way.

From New York Times

After the disease killed more than 5 billion sea stars, the urchin population exploded, devouring kelp and leaving seascapes with almost nothing but the spiny, globular echinoderms.

From Seattle Times

But most echinoderms -- a group of some 7,000 species that includes brittle stars and similarly brainless starfish, sea urchins and sea cucumbers -- have not been tested.

From Science Daily

The study begins to probe a bigger evolutionary question: How did the sea star and its equally-strange echinoderm siblings develop their unique starlike symmetry?

From Scientific American

This at least is the conclusion of a landmark recent paper in the journal Nature, which solved a lingering puzzle about starfish anatomy by turning to the enigmatic echinoderm's genes.

From Salon