Introduction to Sharks
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.
"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."