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Ground sharks are the largest order of sharks, and include a number of common types such as the blue shark, catsharks, swellsharks and sandbar sharks. Members of the orders are characterized by the presence of a nictitating membrane over the eye, two dorsal fins, an anal fin, and five gill slits.
Precise details of the size, age, and growth, such as size at maturity for the gulper shark, are currently unknown. The gulper shark is a slim, relatively long dogfish with two dorsal fins bearing long grooved spines. The second dorsal fin is shorter than the first, and its base is about three-fourths the length of the first dorsal fin.
The order Squaliformes is a large, ancient order of sharks. Sharks from this order have two dorsal fins -usually with spines-, no anal fin, and no nictitating membrane on the eyes. Squaliform sharks are extremely variable in size and shape, and can be found in most marine habitats throughout the world.
Dogfish sharks: 3 31 Dogfish sharks have two dorsal fins, each with smooth spines, but no anal fin. Their skin is generally rough to the touch. [18] These sharks are characterized by teeth in upper and lower jaws similar in size; caudal peduncle with lateral keels; upper precaudal pit usually present; and a caudal fin without a
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 two dorsal fin have rounded apices and are placed far back, with the first originating over the pelvic fin bases. The second dorsal fin is noticeably smaller than the first. The anal fin is less than half the size of the first dorsal fin and placed so that its free rear tip just reaches the base of the caudal fin. The caudal fin is long and ...
The two dorsal fins have straight trailing margins and are spaced well apart. The first dorsal fin is as large or larger than the pelvic fins, originating behind the middle of the pelvic fin bases. The second dorsal fin is slightly smaller than the first but has a longer base. There is a prominent midline ridge along the back, which continues ...
The first dorsal fin is positioned closer to the pelvic than the pectoral fins. The second dorsal fin, nearly equal to the first in size, is located over or slightly forward of the anal fin. No ridge is seen between the dorsal fins. The pectoral fins are long and broad, originating below the space between the third and fourth gill slits.