Animals which spend much of their time in air are said to be arboreal.
For example, birds and insects.

The amoeba is a unicellular (having only one cell) animal which can be classified as an invertebrate.

Animals which live in water are said to be aquatic.
For example, fish.

Animals which live on trees are said to be arboreal.
For example, monkeys and owls.

The auditory nerve carries messages from the ear to the brain.
It aids the ear for the sense of hearing.

Our vision is binocular.
This means that our sense of vision (sight) uses two eyes.

The cochlea is the scientific name for the inner ear.
It is shaped like a snail and 'cochlea' is Latin for 'snail'.
The stirrup touches the cochlea and is part of the middle ear.
The eardrum separates the outer ear and the middle ear.

The part of the alimentary canal which absorbs water is the colon.
The colon is a part of the large intestine.
The colon, caecum and rectum together form the large intestine.

Crustaceans are hard-shelled animals whereas molluscs are also hard-shelled animals but having soft bodies.
Crayfish (a freshwater creature like a lobster) is a crustacean whereas oyster and octopus are both molluscs.

The crocodile is a cold-blooded animal.
The whale, leopard, seal and elephant are all warm-blooded animals.

Animals which are active during the day and rest at night are known as diurnal animals.
For example, bears, deer and elephants.
Animals which are active only during the night are known as nocturnal animals.
For example, cockroaches and owls.

Frogs have external eardrums.
These act as their hearing organs.

The gustatory nerve carries messages from the tongue to the brain.
It aids the tongue for the sense of taste.

In a tadpole (the larva of a frog or toad), the hind legs develop first, followed by the front legs.

Maggots are the larvae of house-flies.

Mammals have mammary glands.
These glands help in the secretion of milk.

Crustaceans are hard-shelled animals whereas molluscs are also hard-shelled animals but having soft bodies.
Mussel (a kind of bivalve animal) is a mollusc whereas crab and shrimp are both crustaceans.

The olfactory nerve carries messages from the nose to the brain.
It aids the nose for the sense of smell.

The optical nerve carries messages from the eye to the brain.
It aids the eye for the sense of vision (sight).

Animals which live on land are said to be terrestrial.
For example, cats, dogs and camels.

A person suffering from this defect of long-sightedness can see distant objects clearly but cannot see nearby objects clearly (they appear blurred).
The scientific name for this defect is hypermetropia.

The lateral lines of fish are sensitive to the vibrations of water.
These lateral lines help the fish to swim in a streamlined manner.

Grass-snakes and slow-worms can be classified as reptiles (reptilia).
'Reptilia' or reptiles is one of the classes of vertebrates.

There are exactly 5 toes on each of the hind feet of a frog.

A bull is color-blind, hence it is unable to distinguish between colors.
So the bull is not angered by the color of a red cloth.
However, it is angered by the movement of a red cloth.

The body of an insect consists of three parts, namely the head, thorax and abdomen.

A person suffering from this defect of short-sightedness can see nearby objects clearly but cannot see distant objects clearly (they appear blurred).
The scientific name for this defect is myopia.