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The evolution of sharks

The very word 'shark' conjures up thought of the Great White that became famous from the series of films called Jaws. There are however more than 350 different species of shark lurking in our oceans ranging in size from around 1 meter to 12 meters for a fully grown Whale shark which is the biggest of all sharks known to man.

Sharks have inhabited the earth for over 400 million years and were around before the dinosaurs roamed the earth. Sharks are so adept at hunting and feeding that they have not really evolved a great deal in the last 150 million years. Some sharks feed on plankton


as their staple diet whereas others feed predominantly on meat. With powerful bodies the shark can swim quickly towards its prey and strike with such ferocity that the victim has little chance of escape.

Sharks are so diverse in type that they can differ from species to species how they produce their young, they range in number from 1 to 100 pup sharks being born at any one time. There are 3 different ways in which they give birth to their 'Pups'. Some lay eggs in a safe place on the sea bed and will then discard them and have no maternal instinct towards ensuring the pup is safe whilst growing, its on its own! Some sharks eggs grow inside the mother shark and will hatch inside her and are born in the same way we humans are. Lastly, pup sharks can develop inside the mother shark like we do. Growing inside the womb to be born as a tiny version of themselves.

Over the centuries sharks have strengthened their hunting skills to be the most feared predator in the sea. Two thirds of the sharks brain is used to enhance its sense of smell to alert the shark that food is nearby. Others have the eyesight of a cat, having developed a mirror like screen over the eyes they can see quite clearly in the murky depths of the ocean. Sensors run along the sharks body, known as the 'Lateral line' which is covered with tiny hairs that sense tiny vibrations in the water to again let the shark know that dinner may be swimming by. The most amazing tool the shark has developed though is the power to feel electrical pulses in the water that are emitted by its prey, this is called the 'Ampullae of Lorenzini' and is a sensor used by a great number of sharks to enhance its hunting skills.

As we know from the films, Sharks have a vast number of teeth that are razor sharp to rip through even the tough skin of a passing seal. Combined with powerful jaws that are controlled by the lower jaw bone, the Shark has little


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The evolution of sharks

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