Fish are the natural aquatic animals which can be found in lakes, pounds, seas,
rivers except very salty water, such as the Dead Sea and the Great Salt Lake of
Utah. Some fish can stay in hot deserts at a temperature of 100°F.
Fish is a cold blooded and can breathe under water by the help of gills. They
can swim efficiently by means of fins which are used for balancing, steering and
braking. But there are some other fishes which can stay out of the water for some
time by the help of lungs. There are 20,000 kinds of fish living under water and
new species of fish are discovered every year and they differ in shape and size.
The size of "Whale Shark" is the largest among all the fishes. It reaches
50 feet in length and about 18,140 kilograms in weight. Many fish eat fishes smaller
to them and are in turn the food of larger fish. However, they depend on planktons
which are the rich pastures of the seas. Fish has a low level brain and have no
ears but they have a hearing material inside the brain by means of which they
can hear and they also have an excellent sense of smelling.
Some fishes
have the capability of changing color according to the surrounding so that they
can make themselves invisible to enemies. A weapon for defending themselves differs
from species to species. Some have great speed, some can change their color, some
consists of electric current which delivers dangerous shock and some have poisonous
tail and so on.
Fishes are related to humans in many ways. Humans consumes
fishes, also do catch them for finding species of fishes for experiment purpose
and also extracts cod-liver oil which is a great source of energy, especially
for children.
