Shark

Shark is one of the biggest fish found in the sea, It is also one of the most dangerous creatures in the sea. A shark has a streamlined body shaped like a torpedo. It has two powerful and stiff tail fins. These fins are spread out like wings. These fins enable it to swim very fast in the sea, Some species like Marco Shark can swim with a speed of 50 to 60 mph. However, unlike other fish Shark can only swim in forwards direction due to stiff fins.

There are many kinds of sharks but only a few of them are very dangerous. Generally, Sharks are found however some live in rivers and lakes too. Sharks generally prefer warm waters. 

Sharks have 40 to 45 teeth in average, and it loses these teeth regularly, in whole life, it can go through 30,000 teeth. Sharks have very sharp sensory organs. They can smell a drop of blood in the water from half a kilometer away. Sharks can smell, taste, see, hear and touch, but most often they use smell to search for their food. Their hearing organs are well developed. They have eyelids too, but their sight is not so good.

Sharks have been living on the earth for nearly 450 million years. A large shark can weigh over seven tonnes, and its extremely powerful jaws are large enough for a man to crawl through. The Whale Shark is usually 18 meters long.