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Dorsal fin of a shark. A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom.Many species of animals possessing dorsal fins are not particularly closely related to each other, though through convergent evolution they have independently evolved external superficial fish-like body plans adapted to their marine environments ...
Dorsal fin diagram with landmarks labeled. 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.
Mackerel sharks, also called white sharks, are large, fast-swimming sharks, found in oceans worldwide. They include the great white, the mako, porbeagle shark, and salmon shark. Mackerel sharks have pointed snouts, spindle-shaped bodies, and gigantic gill openings. The first dorsal fin is large, high, stiff and angular or somewhat rounded.
A large species that often reaches 3.0 m (9.8 ft), the Galapagos reef shark has a typical fusiform "reef shark" shape and is very difficult to distinguish from the dusky shark (C. obscurus) and the grey reef shark (C. amblyrhynchos). An identifying character of this species is its tall first dorsal fin, which has a slightly rounded tip and ...
A small fin, positioned behind the dorsal or anal fins, that is supported by a ray or rays. fluviatile Living in rivers. free rear tips (of fins) The posterior tip of the fin that is closest to the most posterior point of the fin base. frontal ridge A ridge running along the top of the head along the midline. furcate Forked. fusiform
The first dorsal fin is positioned about halfway between the pectoral and pelvic fins. The second dorsal fin is about two-thirds as tall as the first and is positioned slightly ahead of the anal fin. The anal fin is smaller than the second dorsal fin. The dorsal surface of the caudal peduncle bears a crescent-shaped notch at the caudal fin ...
The pectoral fins are large and broad, and the anal fin is larger than the second dorsal fin. The short and broad caudal fin has an indistinct lower lobe and a prominent ventral notch near the tip of the upper lobe. The skin is thick and covered by well-calcified, arrowhead-shaped dermal denticles, which are more sparse in young sharks.
The dorsal fins are small, with the first dorsal fin origin lying behind the pelvic fin origins. There is no anal fin. The caudal peduncle is robust and lacks notches at the caudal fin origins. The asymmetrical caudal fin has an indistinct lower lobe and an upper lobe without a notch in the trailing margin. [9]