Did you know that...

Do you know that sharks need to move constantly to survive?

 
 Most of the fish can pomp water, which is their source of oxygen, through their gills. Sharks however need to swim constantly, so that the water pouring into their mouth would spontaneously flow over their gills.
Shark are speeding through the water restlessly, using a force of a caudal fin. Sometimes a dorsal fin can be spotted, cutting through the water surface – it is a sign that the shark is starting the attack. The fin helps it to steer, dive and keep balance.