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Ctenoid scales can be further subdivided into three types: Crenate scales, where the margin of the scale bears indentations and projections. Spinoid scales, where the scale bears spines that are continuous with the scale itself. True ctenoid scales, where the spines on the scale are distinct structures. Most ray-finned fishes have ctenoid scales.
Acanthomorphs have developed spiny ctenoid scales (as opposed to the cycloid scales of other groups), tooth-bearing premaxilla and greater adaptations to high speed swimming. [ 5 ] The adipose fin , which is present in over 6,000 teleost species, is often thought to have evolved once in the lineage and to have been lost multiple times due to ...
These scales are classified as leptoid scales. The leptoid scales are thin and flexible and cover the extent of the body. Leptoid scales are divided in two groups of specificity. The finescale dace has what are called ctenoid scales, called this because of the cteni that run along the posterior area of the fish. A lateral line system exists on ...
Keeled scales of a colubrid snake (banded water snake; Nerodia fasciata) In zoology, a scale (Ancient Greek: λεπίς, romanized: lepís; Latin: squāma) is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopterans (butterflies and moths), scales are plates on the surface of the insect wing, and provide ...
Cycloid scales are small, oval-shaped scales with growth rings like the rings of a tree. They lack enamel, dentin, and a vascular bone layer. Bowfin and remora have cycloid scales. Ctenoid scales are similar to cycloid scales, also having growth rings, lack enamel, dentin, and a vascular bone layer. They are distinguished by spines or ...
The teleost scales are also then divided into two subgroups which are the cycloid scales, and the ctenoid scales. All these scales have a base of bone that they all originate from, the only difference is that the teleost scales only have one layer of bone.
The head is moderately sized with an almost straight dorsal profile, a short snout and quite large eyes. The mouth is small and oblique with small but strong teeth in the jaws arranged in broad bands with the outer band being enlarged and recurved. Most of the body is covered in very small ctenoid scales and there is a gently curved lateral line.
The scales are mainly ctenoid, although there are non-ctenoid scales typically in the underside and on the back near the head. The upper lateral line has tubed scales which may be reduced in extent and in the middle lateral line the tubed scales are frequently often replaced by pored scales. The caudal fin contains10-14 branched fin rays. [3]