Lamna

Lamna is a genus of mackerel sharks in the family Lamnidae, containing two extant species: the porbeagle (L. nasus) of the North Atlantic and Southern Hemisphere, and the salmon shark (L. ditropis) of the North Pacific. The two species of this genus can keep their blood temperature higher above that of the water surrounding them than other cartilaginous fish, with temperature differences recorded up to 15.6 °C. Among fish, blood temperature regulation only occurs in large, fast species – bluefin tuna and swordfish are bony fish with similar abilities.