The
porbeagle (
Lamna nasus) is a
species of
mackerel shark in the
family Lamnidae, distributed widely in the cold and temperate marine waters of the
North Atlantic and
Southern Hemisphere. In the
North Pacific, its ecological equivalent is the closely related
salmon shark (
L. ditropis). The porbeagle typically reaches in length and a weight of ; North Atlantic sharks grow larger than Southern Hemisphere sharks and differ in coloration and aspects of life history. Gray above and white below, the porbeagle has a very stout midsection that tapers towards the long, pointed snout and the narrow
base of the tail. It has large
pectoral and first
dorsal fins, tiny
pelvic, second dorsal, and
anal fins, and a crescent-shaped
caudal fin. The most distinctive features of this species are its three-cusped teeth, the white blotch at the aft base of its first dorsal fin, and the two pairs of lateral keels on its tail.