Friday, April 29, 2011

The Tiger Shark

Galeocerdo cuvier

Tiger Shark teeth.
The Tiger Shark,  is one of the world's most dangerous sharks. Named for their stripes that fade as the animal gets older, the tiger shark is also known as the "garbage can of the sea". This name comes from the tiger shark's tendency to eat anything and everything that crosses their path. Just to name a few items found in tiger shark stomachs: a tom-tom, a chicken coop, license plates, drums, a goat, a suit of armour. In addition to garbage, tiger sharks eat dolphins, seals, seabirds, marine turtles, sea snakes, fish, sharks, rays, crabs, spiny lobsters, horseshoe crabs, octopus, squid, marine snails, and jellyfish. Their heavily serrated teeth have an indentation which makes the tooth look crooked. This unique tooth shape combined with a large bite force allows for the tiger shark to break the rock hard shell of marine turtles. Tiger Sharks are active at night and enter shallow reefs and lagoons after dusk to feed. The largest tiger shark ever recorded was 18 feet, but there have been some unconfirmed reports of tiger sharks longer than 30 feet! The females mature at 8 years, at 8 to 11.5 ft. Males mature at 7 years, at 7.5 to 10 ft. They are ovoviviparous (the females carry eggs that hatch in the womb, but are not attached by an umbilical cord to the mother) and their gestation period is 13-16 months. They can give birth to anywhere from 10 to 82 pups! However, as with all sharks, they do not care for their children.

note: I do not own any of these pictures.

Sunday, April 17, 2011

The Great White Shark

A Great White Shark off the coast of New Zealand
A gaping White Shark 
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.

note: I do not own any of these pictures.