Aquatic habitat is one of the most important habitats, where a large number of animals live. The aquatic habitat includes both fresh water and salt water habitats.
Adaptive features of aquatic animals are:
(1) Body shape: Body is streamlined and offers the least resistance to motion, like swimming.
(2) Swimming organs: The body is covered with waterproof scales and a slippery substance for reducing the surface tension. The flippers of whale, fins and tail of a fish help in increasing speed and changing direction.
(3) Air bladders: They are present in some fishes. It communicates with pharynx and filled with air.
(4) Respiratory organs are gills in fishes. Gills have the large surface area to extract oxygen dissolved in water.
In the amphibious adaptation, a frog is adapted for both aquatic and terrestrial life.
(i) limbs, through webbed feet, are adapted for swimming.
(ii) Hind limbs are longer than forelimbs.
(iii) Skin is always moist, which helps in breathing when the animal is on land.
(iv) Fertilisation is external.
The animals living on land differ in their habits of living. The walkers and runners have cursorial adaptations, the borrowers have fossorial adaptations, climbers and fliers have arboreal adaptations. Animal living in deserts have desert adaptations.
Xeric adaptations of Desert animals:
Animals such as camels, desert rats, rabbits, foxes, etc. have to adapt in order to overcome, xeric conditions.
Some xeric adaptations are as follows:
(i) Moloch absorbs water, like blotting paper. Its surface is covered by thorn like scales.
(ii) Water cells are developed in the walls of a camel. It uses its entire foot while walking.
(iii) The desert animals do not perspire and conserve water.
(iv) The nostril of camel can be closed like eyelids. The eyelids are modified into the window like structure, which covers the eye.
(v) The ear opening is either small or protected by scales.
(vi) The sense of light, hearing and smell are highly developed.
