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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 ...
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 tail of a shark consists of the caudal peduncle and the caudal fin, which provide the main source of thrust for the shark. Most sharks have heterocercal caudal fins, meaning that the backbone extends into the (usually longer) upper lobe. The shape of the caudal fin reflects the shark's lifestyle, and can be broadly divided into five categories:
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
Ground sharks, like this blacknose shark, have a nictitating membrane which can be drawn over the eye to protect it. Carcharhiniformes / k ɑːr k ə ˈ r aɪ n ɪ f ɔːr m iː z /, the Requiem sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and requiem sharks.
Rough sharks are characterised by two large dorsal fins, each with a sharp spine, and with the first fin placed far forward above the head. Their bodies are compressed, giving them a triangular cross-section. Their skins are even rougher and more prickly than the dogfishes (below). Rough sharks are small to medium in size, ranging from 49 to ...
Savannah Guthrie discussed the "shark sighting" on the Today Show Thursday. Over the past several months, viewers have submitted videos of what appears to be a giant shark fin popping out of the ...
The prickly shark and the bluntnose sixgill shark (pictured) prey on each other's young. The prickly shark is a slow swimmer and has been observed hovering just above the sea floor. [14] A tracking study in Monterey Canyon found that this species exhibits strong diel migration patterns. The sharks were inactive during the day, resting in ...