- 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.
Origin of echinoderm
Examples from the Web for echinoderm
Historical Examples of echinoderm
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.
- 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
- 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.