Of all shark species, Carcharodon carcharias is perhaps the best known and least understood. The white shark is a member of the Mackerel shark family whose members are "point endothermic". This means that they are not truly warm-blooded, but the movement of their muscles warms their blood. Now known more often as the white shark than the Great White Shark, these massive creatures can weigh from 1,500 to 4,500 pounds. Females become mature at the age of 14-16 years old, at 15-16 ft. Males mature at 9-10 years, at 11.5-12 ft. At birth they are 3-5 ft. long. Their gestation period is thought to be 18 months. White sharks are believed to be opportunistic feeders, but here are some of the items they are known to feed on: sharks (though they are not cannibalistic, they do eat smaller shark species), rays, fish, seals, sea lions, dolphins, squid, sea birds, marine turtles, crabs, snails, and whale carrion. Sadly, these beautiful and majestic creatures are vulnerable of becoming extinct. Over fishing combined with slow reproduction rates means dropping shark numbers, not just in Great Whites, but in all shark species.