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Fins allow the sharks to be able to guide and lift themselves. Most sharks have eight fins: a pair of pectoral fins, a pair of pelvic fins, two dorsal fins, an anal fin, and a caudal fin. Pectoral fins are stiff, which enables downward movement, lift, and guidance. The members of the order Hexanchiformes have only a single
The shape, size, position and colour of the dorsal fin varies with the type of billfish, and can be a simple way to identify a billfish species. For example, the white marlin has a dorsal fin with a curved front edge and is covered with black spots. [4] The huge dorsal fin, or sail, of the sailfish is kept retracted most of the time. Sailfish ...
The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder ...
Dorsal fins: Located on the back of the fish, dorsal fins serve to prevent the fish from rolling and assist in sudden turns and stops. Most fishes have one dorsal fin, but some fishes have two or three. In anglerfish, the anterior of the dorsal fin is modified into an illicium and esca, a biological equivalent to a fishing rod and lure.
The term sail or dorsal sail has been used to refer to sail-like structures on the back of various animals. Such animals can also be referred to as sail-backed or fin-backed. Such structures include the following: Neural spine sail – formed by the neural spines of the vertebrae; Dorsal fin – in some aquatic species with tall fins on their back.
According to biologists, the dorsal fin’s size in such shallow water should reveal part of the shark’s back or a second dorsal fin — neither of which are visible.
The first dorsal fin is large, high, stiff and angular or somewhat rounded. The second dorsal and anal fins are minute. The caudal peduncle has a few or less distinct keels. The teeth are gigantic. The fifth gill opening is in front of the pectoral fin and spiracles are sometimes absent.
The crowns of these osteodont teeth are covered with a single layer of enameloid. Hybodont teeth served a variety of functions depending on the species, including grinding, crushing , tearing, clutching, and even cutting. [4] Hybodonts are characterized by having two dorsal fins each preceded by a fin spine.