Shark Facts

1.Sharks have been around for about 400 million years - long before dinosaurs even existed.
2.Sharks have the most powerful jaws on the planet.
3.Sharks never run out of teeth - when one is lost another spins forward from the rows of backup teeth.
4.A shark may use over 20,000 teeth during its life.
5.The Great White Shark rarely partakes in feeding frenzies.
6.Sharks will often eat other sharks.
7.A sharks skeleton is made of cartilage, allowing greater flexibility.
8.A sharks skin is made of denticles - similar to thousands of small shark teeth.
9.The most harmless sharks tend to be the largest, such as the Basking Shark, the Whale Shark and the Megamouth Shark.
10.There are only about 100 Shark attacks on humans each year, resulting in about 10 deaths.

that's all for today, more facts soon :)

which sharks really are dangerous?

There are 3 sharks that can be classified as 'most dangerous'

these are:

>>Tiger Shark
>>Great White Shark
>>Bull Shark

teeth

Shark teeth are embedded in the gums rather than directly affixed to the jaw, and are constantly replaced throughout life. Multiple rows of replacement teeth grow in a groove on the inside of the jaw and steadily move forward as in a "conveyor belt"; some sharks lose 30,000 or more teeth in their lifetime. The rate of tooth replacement varies from once every 8–10 days to several months. In most species teeth are replaced one at a time, except in cookiecutter sharks the entire row of teeth is replaced simultaneously.[7]
Tooth shape depends on diet: sharks that feed on mollusks and crustaceans have dense flattened teeth for crushing, those that feed on fish have needle-like teeth for gripping, and those that feed on larger prey such as mammals have pointed lower teeth for gripping and triangular upper teeth with serrated edges for cutting. The teeth of plankton-feeders such as the basking shark are smaller and non-functional.[8]

sharks

Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs.^[1]

Since that time, sharks have diversified into 440 species, ranging in size from the small dwarf lanternshark, Etmopterus perryi, a deep sea species of only 17 centimetres (6.7 in) in length, to the whale shark, Rhincodon typus, the largest fish, which reaches approximately 12 metres (39 ft 4 in) and which feeds only on plankton, squid, and small fish by filter feeding. Sharks are found in all seas and are common down to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater, with a few exceptions such as the bull sharkand the river shark which can live both in seawater and freshwater.^[2] They breathe through five to seven gill slits. Sharks have a covering of dermal denticles that protects their skin from damage and parasites, and improves their fluid dynamics so the shark can move faster. They have several sets of replaceable teeth.^[3]

Well-known species such as the great white shark, tiger shark, and the hammerhead are apex predators, at the top of the underwaterfood chain. Their extraordinary skills as predators fascinate and frighten humans, even as their survival is under serious threat from fishing and other human activities.