echinodermal

[Eng. echinoderm (q. v.); -al . ] Zool .: Pertaining to the Echinoderm at a. "The harder, spine-clad, or echinodermal species."Owen: Invert. Anim . (1843), Lect. x., p. 113. e-chi-no-der-ma-ta, s. pl. [Gr. echinos a hedgehog, and derma , pl. dermata =the skin.] 1. Zool .: Echinoderms, a cla of animals ostab lished by Cuvier, and placed as the highest of his sub-kingdom Radiata. Prof. Huxley places them along with Scolecid a, temporarily as a primary sub-kingdom intermediate between the Annulosa and the Infusoria. They are more or le radiated, though not so much as the Medusas. While in the larva state there is a tendency to bilateral symmotry, as in insects. Some mature animals, as the Span tag us, have it also. They have a strange metamorphosis, commencing life as free swimming animals, from which after a time the mature form buds forth. They have a leathery integument, often covered with calcareous plates, often taking the form of spines, hence the name Echinoderms, Their skin is perforated with many minute holes, whence hollow tubes or tentacules are protruded for purposes of locomotion. The cla Echinoderm at a is divided into seven orders: Ech i no idea, Asteroidea, Ophiuroidea, Crinoidea, Cystoidea, Blastoidea, and Holothuroidea (q. v.). 2. Palæont.: The Echinoderm at a commenced, as far as is at present known, when the Upper Cam brian rocks were being deposited, and have never since become extinct.