Facts About Sharks - Shark Species, Shark Teeth and Shark Senses

This hub will focus on introducing some interesting facts about sharks, including different shark species, the uncommon growth of shark teeth, the extraordinary shark senses in the water and cancer research on sharks.

This is the first part of the two series hubs on sharks. The second part will provide you with a carefully selected catalogue of shark related products on Amazon, including shark books, shark DVDs, shark toys, shark clothes accessories etc. If you're avid of sharks, do not miss the chance of getting some wonderful shark products from Amazon, or buy those products as unique gifts for your kids, they sure will show great interests in this mysterious marine animal, some will even begin their little biology study of sharks right away!

Sharks have lived on earth for more than 180 million years, evolved even before the dinosaur. Although sharks live in all the oceans of the world, they are usually found in subtropical and tropical waters instead of colder waters.

There are approximately 350 shark species worldwide. Of all the shark species, the whale shark and the basking shark are the largest. The adult basking shark grows to over eight meters long, while the whale shark can reach about thirteen meters long. Both the whale shark and the basking shark feed on plankton and small fish. Blue shark is the fastest in the all the shark species, it can swim through the water at a speed reaching 72 kilometers per hour.

Not all shark species are deadly dangerous to human. However, there are a number of them which have attacked and killed swimmers. These sharks include the great hammerhead, whitetip, lemon, blue, and the great white shark.

The great white shark is said to be of the most ferocious shark species to attack humans. The adult great white shark grows to between five and eight meters long and can weight more than a thousand kilograms. It can swim at a speed of nearly 32 kilometers per hour.

Shark teeth is one of the most unusual aspects of a shark. They are very sharp, wedge-shaped, serrated and can grow as long as five centimeters. It's very common for a shark to have more than four sets of teeth during its lifetime, some even have as many as five or six sets of shark teeth throughout their lives.

The shark teeth are arranged in rows, most sharks have about five rows of teeth at any time. As the shark teeth are worn out and fall out, they are replaced by the next row. Shark teeth are replaced very quickly, some sharks can wear out a full set of teeth in less than six months. In a lifetime some sharks can grow and lose between ten thousand and thirty thousand teeth.

Shark senses are extraordinary under water. The shark has a large brain, extraordinary sense of smell and a well-developed sensory system. On the shark's nose and chin, there are sensory pits which can detect weak electrical fields in the water that are produced by fish and other animals. Even small actions such as the gill action of a fish be detected by the sensory pits of a shark.

In addition to the sensory pits in the shark's nose, the shark also has a lateral sensory system which runs along the length of its body. Sounds made by fish and other animals in the water can be picked up by this sensory system.

Cancer research on sharks have found that sharks do not develop cancer. Marine biologists are studying the shark in hopes of finding clues that may help fight cancer in humans. The shark blood seems to inhibit the growth of bacteria and viruses as well as cancer. Marine biologists are now testing the blood to find our how the shark rids itself of caner-producing agents in hopes of finding clues for the cure of cancer. However, cancer research on sharks are still in progress and it's hoped that new discovery can be applied in human cancer prevention and treatment.

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