• Ganoid scale

     From the Greek g├ínos - luster.
     The bony plates of rhombic firme, covered with a thick layer of ganoid, form a peculiar shell on the fish body. Ganoid scales were mainly found in fossil fish. Of the modern ones, ganoid scales are found in pike and multipurple. In sturgeon fish, it is preserved as a rudiment on the upper blade of the caudal fin.
     Scales of lower ray-finned fishes covered on the outside with a hard, shiny layer of an enamel-like substance called ganoin. A distinction is made between paleonischoid ganoide scales of fossil paleoniscids and modern polypterans, and lepidosteoid ganoide scales of fossil bony ganoids and modern armoured pike. Paleoniscoid ganoid scales have a bony base of interlocking trough-shaped laminae, with dentin rolls along the upper edge. The ganoid laminae grow symmetrically to the laminae of the base. There is no dentin in the lepidosteoid ganoid scales and the bony base is pierced by numerous channels. The shape is usually rhombic. On the upper edge of each scale there is a spike which enters the groove of the scale above it. The scales are arranged in rings, slightly inclined to the longitudinal axis of the body, and form a carapace which, in addition to its protective function, supports the muscles and gives the body the necessary elasticity for movement.

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Ganoid scale

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