DEEP BLUE SHARK MARKINGS SKIN

Squid are the most important prey for blue sharks, but their diet includes other invertebrates, such as cuttlefish and pelagic octopuses, as well as lobster, shrimp, crab, a large number of bony fishes, small sharks, mammalian carrion and occasional sea birds. Records from the Atlantic show a regular clockwise migration within the prevailing currents. It prefers water temperatures between 12 and 20 ☌ (54–68 ☏), but can be seen in water ranging from 7 to 25 ☌ (45–77 ☏). In the tropics, it spreads evenly between 20° N and 20° S. Its greatest Pacific concentrations occur between 20° and 50° North, but with strong seasonal fluctuations. Blue sharks are found off the coasts of every continent, except Antarctica. It lives as far north as Norway and as far south as Chile. In temperate seas it may approach shore, where it can be observed by divers while in tropical waters, it inhabits greater depths. The blue shark is an oceanic and epipelagic shark found worldwide in deep temperate and tropical waters from the surface to about 350 m (1,150 ft).

DEEP BLUE SHARK MARKINGS SKIN

Female blue sharks have adapted to the rigorous mating ritual by developing skin three times as thick as male skin. Courtship is believed to involve biting by the male, as mature specimens can be accurately sexed according to the presence or absence of bite scarring. Females mature at five to six years of age and males at four to five. The gestation period is between nine and 12 months.

They are viviparous, with a yolk-sac placenta, delivering four to 135 pups per litter. The blue shark is also ectothermic and it has a unique sense of smell. The heaviest reported weight for the species was 391 kg (862 lb). Occasionally, a female in excess of 3 m (9.8 ft) will weigh over 204 kg (450 lb). The blue shark is fairly elongated and slender in build and typically weighs from 27 to 55 kg (60 to 121 lb) in males and from 93 to 182 kg (205 to 401 lb) in large females. Occasionally, an outsized blue shark is reported, with one widely printed claim of a length of 6.1 m (20 ft), but no shark even approaching this size has been scientifically documented. Large specimens can grow to 3.8 m (12 ft) long. The male blue shark commonly grows to 1.82 to 2.82 m (6.0 to 9.3 ft) at maturity, whereas the larger females commonly grow to 2.2 to 3.3 m (7.2 to 10.8 ft) at maturity. Like many other sharks, blue sharks are countershaded: the top of the body is deep blue, lighter on the sides, and the underside is white.

Blue sharks are light-bodied with long pectoral fins.

Deep blue shark markings