Fishes
Fishes are
vertebrate animals that live in water. Various kind of differ widely in shape colour and
size. Thus different kind of fishes number more than all other kind of land and water
vertebrates put together.
Some fish look like lumpy rocks,
and others like wriggly worms. Some fish are nearly as flat as pancakes, and others can
blow themselves up like balloons. Many have many different colours that are as bright as
those of the most brightly coloured birds.
All fish have
two main features in common. (1) They have a backbone, and so they are vertebrates. (2)
They breathe mainly by means of gills. Nearly all fish are also cold-blooded animals.In
addition, almost all fish have fins, which they use for swimming. All other water
animals differ from fish in at least one of these
ways.
Amphibians
Amphibians
are a class of animals within the vertebrates. There are about 3,200 kinds of
amphibians, which include species such as frogs, toads, salamanders, and
caecilians.
Amphibians - with a few exceptions - live part
of their life in water and part on land. They hatch from eggs laid in water or moist
ground, and begin life as water-dwelling larvae. Over a period the larvae change into
adults which look very different from the larvae. Most adults spend their lives on
land. while some continue to live in water But almost all return to water to for
mating.
Amphibians are divided into three groups: (1) frogs
and toads; (2) salamanders; and (3)
caecilians.
Reptiles
Reptiles
are cold blooded vertebrate animals with dry, scaly skin, who breathe by means of lungs
There are about 6,500 species of reptiles, Reptiles include alligators, crocodiles,
lizards, snakes, turtles, and the tuatara.
Many reptiles
live a long time, and some turtles have lived in captivity for more than 100 years.
Reptiles live on every continent except Antarctica and in all the oceans except those of
the polar
regions.
Birds
Birds
are animals with feathers. There are no other animals with feathers. Bird are generally
able to fly and achieve great speed. The fastest birds can fly at speed exceeding 160
kilometers per hour. However, not all birds can fly.
There
are about 9,300 species of birds. The smallest bird is the bee hummingbird, which is
about 5 centimetres long. The largest bird is the ostrich, which may grow to about 2.5
metres
height.
Mammals
Mammals
are vertebrates that feeds its young on the mother's milk. There are about 4,500 kinds
of mammals including human beings.
Mammals live almost everywhere on
land as well as in water. Blue whale, the largest animal that ever lived, is a mammal,
measuring more than 30 metres long and weighing more than 150 tons. The smallest mammal
is the Kitti's hog-nosed bat of Thailand which weighs only about 2
grams.
Mammals differ from all or most other animals in
five major ways.
- Mammals feed their babies on
the mother's milk.
- Most mammals give their young more
protection and training than other animals do.
- Only
mammals have hair. All mammals have hair at some time in their
life.
- Mammals are
warm-blooded
- Mammals have a larger, more well-developed
brain than other animals do.