Mammals
.
1. Mammals are warm-blooded animals.
2. The body is divisible into the head, neck, thorax, and abdomen
2. They give direct birth to young ones. Few mammals lay eggs (Platypus) Some mammals
(Kangaroo) give birth to immature young ones.
3. They found in a variety of habitats- forests, mountains, water, polar ice caps, deserts, etc.
4. Presence of mammary glands.
5. Presence of fur on the body.
6. Presence of pinnae.
7. Presence of forelimb and hind limbs used for running, climbing, walking swimming, flying etc.
8. Presence of different kinds of teeth
9. Heart is four-chambered.
10. Respiration by lung.
11. They are homoeothermic animals (warm Blooded) maintains constant body temperature.
12. Sexes are separate.
13. Fertilization is internal.
14. They give direct birth to young ones with few exceptions.
15. Development is direct.
Examples: Oviparous – Platypus; Viviparous – Kangaroo, Flying fox), Delphinus (Common dolphin), Balaenoptera (Blue whale), etc.
1. Class Mammalia is classified into three sub-classes , which are :
Sub-class: Prototheria
2. They do not give birth but they lay eggs and incubate them, The mother suckles its young with milk secreted from its mammary glands on its abdomen, They have a cloacal opening through which urine, feces, and eggs emerge, Such as Duck-billed platypus and Spiny ant-eater.
Sub-class: Metatheria
3. They give birth immature youngs, The mother suckles its youngs from nipples found inside a special pouch at the bottom of its abdomen where it keeps its young until they become fully grown, Such as Kangaroo.
Sub-class: Eutheria
4. They are placental mammals that give birth fully developed youngs, Their mother suckles its young with milk secreted from its mammary glands.
5. Eutheria includes many animals that are headed by human and it is divided into many orders , the most important ones are Edentata , Insectivora , Carnivora , Perissodactyla , Artiodactyla , Cetacea , Rodentia , Lagomorpha , Chiroptera , Proboscida and Primates .
