They were revolved very earlier from the jawless fishes. They have marine water ancesstors.Their skin have placid scales. The placid scales have plates. They corer the whole body of the fishes. It makes skin very tough.
These scales can also reduce the frication of water when sharks move in water forward. The teeth of sharks are also very sharp. They have two rows of teeth upper row and lower row.
They can replace their old teeth with the passage of time. Their tooth plays an important role in their prey capturing. They are filter feeders. They prey on the small fishes. They have very strong tricks of capturing food.
They use their strong teeth and forceful body. They can be even dangerous to human. It can swallow human as a whole like an alligator. While hunting sharks the hunter should be careful. They can drag the hunter into the open sea from their boat and can bite the hunter in very dreadful way.