Astonishing Facts About Sharks

By [http://ezinearticles.com/?expert=Masha_Silko]Masha Silko
The majority of people think of a shark as a violent huge predator with super sharp teeth ranging the ocean in search of food. But in fact there are more than 400 very different species. Nine hundred meters below the ocean surface lives the smallest shark: Dwarf Lanternshark. It grows to a maximum of 17 centimeters. So probably such image of a hunter in a constant search of food is the result of Hollywood movies and especially Steven Spielberg's "Jaws".
A creature of many contradictions, a shark does not have a single bone in it's body, instead it has a skeleton made of cartilage. Sharks keenest sense - is smell. Their olfactory ability is well known. It can detect one drop of blood in a million drops of water (100 liters) and can smell blood 0.4 km away. They have very good color vision and directional hearing. Digestion process can take a long period of time as the food moves from the mouth to a 'J' shaped stomach, where it is stored and initial digestion occurs. Most of the sharks live for about 25 years. In general, they swim at a speed of 8 kilometers per hour but when feeding or attacking, thy reach up to 19 kilometers per hour.
Contrary to the common idea that sharks are instinct-driven animals, studies showed that many species have social and problem-solving skills.
Sharks behavior is increasingly becoming a matter of deep investigation for many researches. Most sharks are harmless to people. Out of 400 shark species, only two dozen are in any way really dangerous to us. Scientists though still don't know for sure why sharks sometimes attack humans. One of the theories is that sharks may mistake the sound of swimming humans for that of injured fish. The most studied sharks are Lemon sharks as they are able to survive in captivity and are in the list of the most aggressive towards human sharks. There were 22 reports of Lemon sharks attacks since 1850. Luckily none of them were fatal.
As estimated, around 100 million sharks are being killed annually, primarily for their fins. According to CNN "There are creatures more predacious than sharks: Humans." Shark fin soup is a delicacy for the wealthy people on special occasions and it has been part of Chinese culture for centuries. According to Peter Knights, director of WildAid International "These are ecosystems that have evolved over millions and millions of years. As soon as you start to take out an important part of it, it's like a brick wall, you take out bricks [and] eventually it's going to collapse."
Oceans undoubtedly depend on sharks as they help to manage it's ecosystem. Sharks have been swimming in the world's oceans for more than 400 million years, but nowadays due to commercial fishing some species are in danger of extinction. Sharks became the unfortunate victim of man-hungry stereotype the world created for them. But in fact what the society should really fear is a world without   rel=nofollow [http://species.com/content/smart-sharks]sharks
Masha Silko a writer for [http://www.species.com]Species.com, the natural science website that covers the world's species, animals, plans, and environmental issues.
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