*Whales take in air less frequently than land mammals, and they can hold their breath for extraordinarily long periods during their dives. Although their lung capacity is no greater than that of land mammals of equivalent size, whales take deeper breaths and extract more oxygen from the air they breathe. Unlike the seal, which exhales before diving, whale’s lungs are still partially inflated. The whale \’s nostrils are modified to from a blowhole at the top of the head. The skin immediately surrounding the blowhole has many specialized never ending. Which are very sensitive to the change as the blowhole breaks the water. The whale often breathes in and out again very rapidly; in the fraction of a second that blowhole is above the surface. The blowhole is closed when the animal is submerged. When a whale surfaces and exhales, a spout of water or 1blow’ can be seen.

Blue whale

*The world’s heaviest marine mammal is the blue whale. It can measure 30 meters long and weighs more than143 tons. Amazingly, this gentle giant only eats krill-small, shrimp- like animals. During the summer, when food is plentiful, a blue whale can eat about 4 tons of krill each day. To catch the krill, whale gulps as much as 64, 600 liters of sea water into its mouth at one time!

• There are about 25000 species of fishes of many different shapes and sizes.
• Fishes, like birds, mammals and reptiles, are vertebrates.
• All fishes in water, although a few can some on land for a short while.
• Fishes have nostrils but they are used only for smelling and not breathing.
• Nearly all fishes swim wriggling the rear part of the body and the tail fins. The other fins are used for balancing and steering.
• The `puffer’ fish has scales like spines and it blows itself up to make a prickly ball. Very deep parts of the ocean are pitching dark. Some fish living here have rows of lights on their bodies.
• The angler fish a long spine which hangs over its mouth like a rod. There is light at the tip of the rod that attracts the prey.
• The mudskipper lives in tropical seas and some up on the beach to look for food.
• The lung fishes have a kind of lung besides gills. When the river drives up they burrow into the mud and breathe through the lungs.
• The flying fish can glide through the air for hundreds of meters. If it is chased by a hunting fish, it shoots out of water and spreads its large fins like wings.
• Sometimes you can tell the age of a fish by counting the rings on one of its scales.