The blue shark prionace glauca
is the most wide ranging shark
species in the world and is found in all temperate and tropical seas. It can attack humans but generally only those in some form of difficulty.
Appearance: The blue shark is reasonably large growing up to 12.5 feet (3.8m) in length. It has a very pointed snout and a sleek tapered body with elongated fins. They have dark blue backs, light blue sides, and white bellies. They are frequently confused with the shortfin mako shark but the blue shark has smaller gills and longer fins.
Behaviour: Blue sharks are among the fastest sharks and are capable of leaping clear of the water, which is one of the reasons they are frequently confused with mako sharks, some say they can reach top speeds of 60 mph but more realistic estimates put the top speed at 22 mph. The shark's diet consists primarily of squid and fish, however they are opportunistic feeders and will eat almost anything including humans. They have serrated teeth to help them to get a grip on the squid. Feeding primarily takes place during the day but increased feeding at night has been reported in recent years. They are often found cruising on the surface at low speeds but they can reach their top speed when excited or feeding. The migration patterns of blue sharks are complex and are not currently understood. Curiously blue sharks occasionally form in large groups of the same gender and roughly the same size, no one knows why they do this. They are found in all temperate and tropical seas at depths of up to 1000 feet, the depths where they are most commonly found depend on where they find the water temperature most comfortable.
Reproduction: Blue sharks give birth to live young, between 4 and 100 pups depending on the size of the mother. They are nourished in the womb by a yolk sack placenta attached to the uterine wall. When born they young are just over 1 foot in length, they reach sexual maturity at 7 feet, which is at about 5 years of age in males and 6 years in females. The sharks mate in summer and the young have a gestation period of 9-12 months. Maximum age is reckoned to be around 20 years but there is no way to tell for sure. Thanks to the shark's large litters they are one of the less threatened of the large shark species.