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Denticles are body surface structures found on some fish and insects.
Fish
Denticles or placoid scales are small outgrowths which cover the skin of many cartilaginous fish including sharks. They are similar in structure to teeth, and teeth may have evolved from denticle-like structures in primitive fish. The shape of denticle varies from species to species and can be used in identification. In most biological nomenclature, a scale (Greek lepid, Latin squama) is a small rigid plate that grows out of an animals skin to provide protection. ...
Orders see text The Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nostrils, scales, two-chambered hearts, and skeletons made of cartilage. ...
Orders Carcharhiniformes Heterodontiformes Hexanchiformes Lamniformes Orectolobiformes Pristiophoriformes Squaliformes Squatiniformes Sharks (superorder Selachimorpha) are fish with a full cartilaginous skeleton[1] and a streamlined body. ...
Types of teeth Molars are used for grinding up foods Carnassials are used for slicing food. ...
Shark skin is covered in denticles, and can therefore be as rough as sandpaper; some societies have in fact used it as such for many years (see Oroshigane). Most point backward, so stroking a shark from head to tail produces a smooth feeling. However, stroking the skin in the opposite direction reveals the rough texture. An interesting exception is the Basking Shark [Cetorhinus maximus]. The crowns seem to point every which way, rather than towards the tail. Sharks have been observed to use their skin to inflict wounds on prey. sheets of sandpaper Sandpaper is a form of paper where an abrasive material has been fixed to its surface; it is part of the coated abrasives family of abrasive products. ...
Orishigane grater made with shark skin Oroshigane (おろし金 or 下ろし金, Literally: grating-metal), also known as oroshiki are graters for use in the Japanese kitchen. ...
Studies have found that the denticles create tiny vortices that reduce drag to make swimming more efficient. Denticles also allow sharks to swim silently compared to other fish that generate considerable noise when they ply the water. Vortex created by the passage of an aircraft wing, revealed by coloured smoke A vortex (pl. ...
In Japan, traditional sword-makers used shark-skin for the hand-grips of swords, to make them less likely to slip in the hand. Diagram showing the parts of a katana Katana (刀) is the word for sword in the Japanese language. ...
Insects  A. Diagramatic representation of a cross section through the surface epithelium of a body segment of a Drosophila larva. B. Diagramatic representation of two adjacent denticle bands of two adjacent body segments. C. Diagramatic representation of the denticle pattern on the ventral body surface of an early Drosophila larva. Denticles on insects are cuticular spikes projecting from body surface epithelial cells. The denticles of Drosophila larvae are present in bands on each body segment. During embryonic development, cells are directed to either make or not make a denticle depending on the pattern of expression of morphogens. The Wingless protein is produced by a stripe of cells (w, in the figure to right) in each segment. It is released from those cells and acts on nearby cells where it prevents denticle production resulting is a band of "naked cuticle". Orders See taxonomy Insects are invertebrates that are taxonomically referred to as the class Insecta. ...
In biology, cuticle or cuticula refers to a more or less tough (but flexible) non-mineral covering of an organism, or part of it. ...
Types of epithelium This article discusses the epithelium, an animal anatomical structure. ...
Type Species Musca funebris Fabricius, 1787 Drosophila is a genus of small flies whose members are often called small fruit flies, or more appropriately vinegar flies, wine flies, pomace flies, grape flies, and picked fruit-flies. ...
Morphogenesis is also the name of a band. ...
The wnt signalling pathway is a network of proteins that has been implicated in embryogenesis and cancer. ...
See also The hedgehog signaling pathway is one of the key regulators of animal development conserved from flies to humans. ...
Parts of a tooth, including dentin Dentin (BE: dentine) is the substance between the enamel (substance in the crown) or cementum (substance in the root) of a tooth and the pulp chamber. ...
External links - Microphotograph of skin
- Biology of Sharks and Rays, Skin of the Teeth
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