placoid scale

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• placoid scale — a type of scale, typically thorn shaped, found on the skin of Elasmobranchii and claspers of Holocephali. Consists of a spine and a basal plate which is usually rhomboidal. It contains a pulp cavity and is composed of an inner layer of dermal… …   Dictionary of ichthyology

• scale — 1) a small, stiff, typically plate like body in the skin of fishes, serving to protect, colour, and support the body. May be modified into spines, tubercles, bony plates, an exoskeleton, reduced or even lost. Phylogenetically absent in Amphioxi… …   Dictionary of ichthyology

• scale — scale1 scaleless, adj. scalelike, adj. /skayl/, n., v., scaled, scaling. n. 1. Zool. a. one of the thin, flat, horny plates forming the covering of certain animals, as snakes, lizards, and pangolins. b. one of the hard, b …   Universalium

• Scale (zoology) — In most biological nomenclature, a scale (Greek lepid , Latin squama ) is a small rigid plate that grows out of an animal s skin to provide protection. In lepidopteran (butterfly and moth) species, scales are plates on the surface of the insect… …   Wikipedia

• placoid — adj. & n. adj. 1 (of a fish scale) consisting of a hard base embedded in the skin and a spiny backward projection (cf. CTENOID). 2 (of a fish) covered with these scales. n. a placoid fish, e.g. a shark. Etymology: Gk plax plakos flat plate …   Useful english dictionary

• placoid — adjective Etymology: Greek plak , plax flat surface Date: 1842 of, relating to, or being a scale of dermal origin with an enamel tipped spine characteristic of the elasmobranchs …   New Collegiate Dictionary

• Fish scale — For other uses, see Fish scale (disambiguation). The cycloid scales of a common roach (Rutilus rutilus). The row of lateral line scales is visible in the lower half of the image. The skin of most bony and cartilaginous fishes are covered by… …   Wikipedia

• odontoid — placoid scale (a type of scale, typically thorn shaped, found on the skin of Elasmobranchii and claspers of Holocephali. Consists of a spine and a basal plate which is usually rhomboidal. It contains a pulp cavity and is composed of an inner… …   Dictionary of ichthyology

• Ichthyology terms — Ichthyology uses several terms that are unique to the science.Contents: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z NOTOC A * Abdomen: belly * Abdominal: pertaining to the belly * Actinosts: a series of bones at the base of the pectoral… …   Wikipedia

• dermal denticle — a small, tooth like, dermal scale in the skin of Elasmobranchii (except Torpedinidae) and the claspers of Holocephali. Also called more commonly placoid scale, although dermal denticle is more correct anatomically …   Dictionary of ichthyology

• neck canal — the one or more ducts in the neck of a placoid scale which radially join the pulp cavity with the exterior and which serve during formation of the scale to contain blood vessel loops …   Dictionary of ichthyology