Question

The animals whose body is covered with hair are called as
A. Aves
B. Reptiles
C. Amphibians
D. Mammals

Answer 1

Hint: Hairs are a thread like outgrowths which grows from the epidermis of the skin. Hairs help the animal to protect themselves from the extreme climatic conditions. In addition, they also aid in maintaining a constant body temperature which is necessary for an organism to survive.

Complete answer:
> Option A:
The Aves are warm blooded vertebrates, with forelimbs which are modified into wings. They have feathers all over their body and no hairs. Thus, option [A], is incorrect.

> Option B:
The reptiles are vertebrates which are four legged. They lay eggs, and their skin is covered with scales and not hairs. Thus, option [B], is incorrect.

> Option C:
The amphibians are cold blooded vertebrates and they fertilize eggs outside their body. They could live both on land and water, and they breathe via their skin and partial gills. Thus, option [C], is incorrect.

> Option D:
The mammals are warm blooded vertebrates and have the capability to produce amniotic eggs. In most mammals, hairs form a thick coat over their skin, whereas humans are mammals which have rare body hairs. Having hairs on the body is a mammalian characteristic.
Hence, the correct answer is option (D).

Note: Mammals are heterodont. Neocortex is present in their brain. They have cervical vertebrae. Mammals respire through lungs. Their skull is a dicondylic type, and the trunk is divided into abdomen and thorax. On their lower jaw only a single bone is present. A four chambered heart is present in mammals.