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They have a rigid, usually spherical body bearing moveable spines, which give the class the name Echinoidea (from the Greek ἐχῖνος ekhinos 'spine'). [5] The name urchin is an old word for hedgehog, which sea urchins resemble; they have archaically been called sea hedgehogs.
Etymology. The name echinoderm is from Ancient Greek ... Ophiuroidea (brittle stars, with around 2,300 species), Echinoidea (sea urchins and sand dollars, ...
With the advent of cladistics, the taxonomy of echinoderms was re-evaluated, finding new support for both Pelmatozoa (in its original sense, per Leuckart, encompassing only stalked forms) and Eleutherozoa, with Echinozoa now having its modern contents of Echinoidea as the sister to a clade containing Holothuroidea and the extinct (and possibly ...
Etymology [ edit ] The genus name Clypeaster is derived from the Latin “clypeus” (meaning round shield ) and “aster” (meaning star ), with reference to the shape of these organisms.
Echinus is a genus of sea urchins.Sea urchins are echinoderms that are typically spherical or flattened with a covering of spine-like structures. Sea urchins tend to be important members of their ecosystems by grazing on other organisms and stabilizing populations.
Ambulacraria / ˌ æ m b j uː l ə ˈ k r ɛər i ə /, or Coelomopora / s iː l ə ˈ m ɒ p ə r ə /, is a clade of invertebrate phyla that includes echinoderms and hemichordates; [1] a member of this group is called an ambulacrarian.
This article about a sea urchin is a stub. You can help Wikipedia by expanding it.
Perischoechinoidea is a subclass of primitive sea urchins that were abundant in the Palaeozoic seas. However, the great majority of species died out during the Mesozoic, as the more advanced euechinoid sea urchins became common.