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Introduction to Sharks
"Are you going in there with that shark Harriet?".
"Yes Heming, I need to collect some
important data.
Do you want to help me?"
"No Harriet I don't know how to swim." | Out
of all the species walking, flying, slithering or swimming, there aren't many who have been around as long, survived as well,
or come in so many shapes and kinds as the shark. The earliest evidences of sharks are isolated spines, teeth and scales that
appeared about 430 million years ago in the Silurian Period, known as the "Age of Fishes". Sharks have a sleek, streamlined
design which helps them swim without using up a lot of energy.They certainly need to conserve their energy because they never
really sleep and most of them never stop swimming.
Some sharks are fierce predators, and would be happy to eat you if they encountered you. Almost any shark six feet
or longer is a potential danger, but three species have been identified repeatedly in attacks: the Great White Shark, the Tiger Shark and the Bull Shark . All three live world wide, reach large sizes and eat large prey such as marine mammals or sea turtles. But most sharks never
grow longer than five feet and never even see anyone with legs and arms anyway. People kill thousands more sharks every year
than sharks kill people.
Sharks take about as long to mature as we do. Some of them become adults in their teens. A mother shark carries her
babies inside her body while they develop, sometimes for more than a year. Even so, some sharks are born inside an egg which
they have to crack open. They spend early portions of their lives in nursery grounds. Some of the advantages sharks have over
people is that they keep growing new teeth, they don't have breakable bones, and they are not prone to get cancer. Sometimes
sharks are referred to as swimming computers because of the six senses which they possess: vision, hearing, vibration, smell, taste and electro-perception.
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