Mammals are found in a variety of habitats: polar ice caps, deserts, mountains, forests, grasslands and dark caves. Some of them have adapted to fly or live in water. The most unique mammalian characteristic is the presence of milk producing glands (mammary glands) by which the young ones are nourished. They have two pairs of limbs, adapted for walking, running, climbing, burrowing, swimming or flying. The skin of mammals is unique in possessing hair. External ears or pinnae are present. Different types of teeth are present in the jaw. Heart is four chambered. They are homoiothermous. Respiration is by lungs. Sexes are separate and fertilisation is internal. They are viviparous with few exceptions and development is direct (Oviparous : Ornithorhynchus (Platypus)).
Examples of Mammals :
- Pteropus (Flying fox)
- Camelus (Camel)
- Macaca (Monkey)
- Rattus (Rat)
- Canis (Dog)
- Felis (Cat)
- Elephas (Elephant)
- Equus (Horse)
- Delphinus (Common dolphin)
- Balaenoptera (Blue whale)
- Panthera tigris (Tiger)
- Panthera leo (Lion)
- Examples: Duck billed Platypus, Spiny ant eater
- Examples: Kangaroo (Macropus), Opossum
- Order Chiroptera: large bat Pteropus (Flying fox), Small bats that suck the blood of mammals Vampires
- Order Insectivora: Moles, Shrews, Hedgerogs
- Order Rodentia: Rat, mice, squirrels, Porcupine
- Order Lagomorpha: Hares, Rabbits
- Order Pholidota : Scaly anteaters or pangolins
- Order Cetaceae: Whales, dolphins
- Order Proboscidae: Indian elephant, African elephant
- Order Ungulata (Hoofed Animals) divided into two sub orders
Artiodactyla: Pig, goat, sheep, cattle, Hippopotamus, deer, camel, giraffe, antelope
- Order Carnivora: Cats, Dogs, Wolves, Foxes, Tigers, Lions, Leopards, bears
- Order Primata: Lemur, tarsiers, lorises, monkeys, apes and man