Search results
Results from the WOW.Com Content Network
Unlike traditional scales, sharks have placid scales, known as denticles. Denticles are V-shaped and are made of layers of dentine and a surface of enamel. [24] Riblets are sockets in the shark's skin which hold the denticles. [22] These denticles on the skin allow for the shark to move quietly, swiftly, and almost effortlessly.
In many respects, it had a shark-like appearance. However, it is best known for its unusually shaped dorsal fin, which resembled an anvil or ironing board. Small spikes (enlarged versions of the dermal denticles commonly covering shark skin) covered this crest, and the ratfish's head as well. [8]
A shark tooth contains resistant calcium phosphate materials. [7] The most ancient types of shark-like fish date back to 450 million years ago, during the Late Ordovician period, and are mostly known by their fossilized teeth and dermal denticles. [5]
The dermal denticles of a lemon shark, viewed through a scanning electron microscope. Unlike bony fish, sharks have a complex dermal corset made of flexible collagenous fibers and arranged as a helical network surrounding their body. This works as an outer skeleton, providing attachment for their swimming muscles and thus saving energy. [33]
Both sets of denticles are smooth, monocuspid and curved posteriorly. The denticles on the head are relatively uniform in size (about as high as the central cusps in the teeth), and rounded in cross section. The denticles on the edge of the dorsal fin have polygonal bases and are fitted together in a mosaic pattern. In the male, the denticles ...
The skin has a dense, uniform covering of non-overlapping dermal denticles measuring up to 0.4 cm (0.16 in) across, which are never fused together as in the bramble shark. Each denticle is thornlike, with strong ridges running down the central spine and radiating out over the star-shaped base. The denticles beneath the snout are very fine in ...
Each denticle is thornlike in shape, with ridges radiating out from the central point over the base. As many as ten denticles may be fused together to form multi-pointed plates. The underside of the snout and the area around the mouth is densely covered by small denticles in sharks under 90 cm (35 in) long; these denticles become larger and ...
The horn shark's dermal denticles are small and smooth, numbering some 200/cm 2 on the back in adults. [2] The dorsal coloration consists of various shades of gray or brown with many small dark spots, though these may be absent in older sharks; the underside is yellowish.