Fish
Fishes are vertebrates and marine animals. They live in water and can also be found in ponds etc. There are two kinds of fish that are
1. Cartilaginous Fishes
Fish with gristly skeleton are known as Cartilaginous Fishes. Shark is an example of Cartilaginous Fish.
2. Bony Fish
Fish that have skeleton made up of true bones are called Bony Fishes.
Stream Lined For swimming:-
Water has 8 times more density than air so fishes have to work a lot to swim. The body of fishes is designed in a manner that they can cut off water easily. Swimming is although difficult in ponds full of clay. The fishes that go fast in those ponds are very stream lined like tunny Fish and Mackerel Fish. They have crescent-shaped tail while the fishes that can not move fast have square tails.
Life cycle of a Fish:
Some fishes born alive while some hatch from eggs. There is a specific breeding season fishes. This season depends upon temperature and light. Most of the fishes lay eggs and majority of the eggs are fertilized outside the body. Usually Fishes do not take care of their young ones but there are some kinds of male fishes which make families.
The senses of Fish:
Like us fishes also have five senses example; sight, scent, taste, touch and hearing. Most of the fishes have eyes on left side of their head which gives them over all vision but they have to turnaround to look behind.
Food for Fish:
Freshwater fish eat all sorts of food including water plants, snails, worms, insects and their larvae, and other fish. Some fish, like grey mullet, are called detritus feeders. They suck up mud from the river bed and digest from it the huge numbers of tiny organisms living there. In the open sea, where there are no rooted plants, most fish are flesh-eaters. Some feed on plankton and are called filter feeders. They take a mouthful of water and plankton, and push it out over the gills. The plankton is filtered out, and the fish then swallows it. This saves energy, as the fish uses the same action to breathe and feed. Even some very large fish, such as basking sharks, are filter feeders. Other species eat shrimps, squid, or other fish. Most deep sea fish have huge mouths and teeth and some can swallow creatures bigger than themselves. They have few chances to feed and may not eat again for months.

Sharks