Question

Why are mammals considered advanced animals?

Answer 1

Hint: Mammals belong to the class Mammalia which is a group of homeothermic tetrapod vertebrates, having a covering of epidermal hair and mammary glands in females for suckling the young ones. Mammals evolved from early reptiles before the origin of birds during the Triassic period more than 200 million years back. Class Mammalia consists of more than 4000 species.

Complete answer:
Mammals are considered advanced animals due to the following characteristics:
1. Homeothermy.
2. The body temperature is above the normal room temperature. Enzymes function at their optimum making mammals more active.
3. Presence of sweat glands which lowers the body temperature if the external temperature is high.
4. Covering of epidermal hair to prevent heat loss if the external temperature is low.
5. To begin digestion in the buccal cavity, true solitary glands occur.
6. Respiratory and digestive tracts are separated by the presence of secondary plates.
7. During the passage of food epiglottis cover the glottis.
8. Inspiration and expiration is aided by the presence of the diaphragm.
9. Four chambered hearts.
10. Complete separation of oxygenated and deoxygenated blood.
11. Pinna or external ear is present to pick up sounds.
12. The cerebrum and cerebellum are larger.
13. For complete safety, the development of the fetus is intrauterine.
14. Development of mammary gland for the nourishment of neonates.

Note:
Mammals occur all over the earth in forests, polar regions, deserts, on land, in water, inside burrows, on mountains, trees, caves, and flying in the air. The body is divisible into head, neck, trunk, and tail, bearing two pairs of pentadactyl jointed appendages, forelimbs, and hind limbs. The exoskeleton consists of keratinized structures like hair, scales, claws, spines, horns, hoofs, etc. Axial and appendicular endoskeleton is mainly made up of bones, with cartilages occurring at places.