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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 ...
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.
The sandbar shark (Carcharhinus plumbeus), also known as the brown shark or thickskin shark, is a species of requiem shark, and part of the family Carcharhinidae, native to the Atlantic Ocean and the Indo-Pacific. It is distinguishable by its very high first dorsal fin and interdorsal ridge. [2]
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.
A small shark typically measuring 1.3 m (4.3 ft) long, the blacknose has a typical streamlined "requiem shark" shape with a long, rounded snout, large eyes, and a small first dorsal fin. Its common name comes from a characteristic black blotch on the tip of its snout, though this may be indistinct in older individuals.
An identifying character of this species is its tall first dorsal fin, which has a slightly rounded tip and originates over the rear tips of the pectoral fins. The Galapagos shark is an active predator often encountered in large groups.
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 sizable first dorsal fin is high with a curving S-shaped rear margin, and originates over the free rear tips of the pectoral fins. The second dorsal fin is relatively large with a short rear margin, and is placed opposite the anal fin. There is no ridge between the dorsal fins. This shark is a pale grayish-brown above and white below, with ...