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The Collaborative International Dictionary
Echinoderm

Echinoderm \E*chin"o*derm`\, n. (Zo["o]l.) One of the Echinodermata.

Douglas Harper's Etymology Dictionary
echinoderm

1834, from Modern Latin Echinodermata, name of the phylum that includes starfish and sea urchins, from Latinized form of Greek ekhinos "sea urchin," originally "porcupine, hedgehog" (see echidna) + derma (genitive dermatos) "skin" (see derma); so called from its spiky shell. Related: Echinodermal.

Wiktionary
echinoderm

n. Any member of the Echinodermata, a group of radially symmetric, spiny-skinned marine animals. Examples of echinoderms include seastars, sea urchins, sea cucumbers, crinoids, and sand dollars.

WordNet
echinoderm

n. marine invertebrates with tube feet and calcite-covered five-part radially symmetrical bodies

Wikipedia
Echinoderm

Echinoderm is the common name given to any member of the PhylumEchinodermata (from Ancient Greek, ἐχῖνος, echinos – "hedgehog" and δέρμα, derma – "skin") of marine animals. The adults are recognizable by their (usually five-point) radial symmetry, and include such well-known animals as starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes (a superphylum), after the chordates (which include the vertebrates, such as birds, fishes, mammals, and reptiles). Echinoderms are also the largest phylum that has no freshwater or terrestrial (land-based) representatives.

Aside from the hard-to-classify Arkarua (a Precambrian animal with echinoderm-like pentamerous radial symmetry), the first definitive members of the phylum appeared near the start of the Cambrian.

The echinoderms are important both biologically and geologically. Biologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. The more notably distinct trait, which most echinoderms have, is their remarkable powers of regeneration of tissue, organs, limbs, and of asexual reproduction, and in some cases, complete regeneration from a single limb. Geologically, the value of echinoderms is in their ossified skeletons, which are major contributors to many limestone formations, and can provide valuable clues as to the geological environment. They were the most used species in regenerative research in the 19th and 20th centuries. Further, it is held by some scientists that the radiation of echinoderms was responsible for the Mesozoic Marine Revolution.

Usage examples of "echinoderm".

Then it was on the radiates, echinoderms, acalephes, polypes, entozoons, sponges, and infusoria, that he had for such a long time burned the midnight oil?

Some kind of highly developed giant nematode or land-based echinoderm, he decided as he turned to examine the motionless carcass.

Beyond them lay slopes of some blackish slag-like material which were dotted with lovely coloured creatures, holothurians, ascidians, echini and echinoderms, as thickly as ever an English spring time bank was sprinkled with hyacinths and primroses.

A thousand beautiful ascidians and echinoderms of every joyous colour and fantastic shape peeped out from amid this herbage, which was alive with strange crustaceans and low forms of creeping life.

I see the free-swimming larvae of the echinoderms developing into the radially-symmetrical forms of adulthood.

The creature displayed qualities reminiscent of both coelenterate and echinoderm.