Class : Mammalia

Habitat: They 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.

Examples:

Oviparous- Ornithorhynchus (Platypus) – Egg laying mammal.

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Viviparous – Gives birth to young ones.

  • Elephas (Elephant)
  • Equus (Horse)
  • Delphinus (Common dolphin)
  • Balaenoptera (Blue whale)
  • Panthera tigris (Tiger)
  • Panthera leo (Lion)
  • Macropus (Kangaroo)
  • Pteropus (Flying fox)
  • Camelus (Camel)
  • Macaca (Monkey)
  • Rattus (Rat)
  • Canis (Dog)
  • Felis (Cat)

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Body characteristics:

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  • Body is divided into head, neck, trunk and tail.
  • Trunk is internally divided by a diaphragm into thoracic and abdominal cavities.
  • The most unique mammalian characteristic is the presence of milk producing glands (mammary glands) by which the young ones are nourished. They are functional in females, but vestigial in males.
  • They have two pairs of limbs, adapted for walking, running, climbing, burrowing, swimming or flying.
  • The skin of mammals is unique in possessing hair. The skin also possesses sweat and sebaceous glands.
  • External ears or pinnae are present.
  • Different types of teeth are present in the jaw.
  • Heart is four-chambered (2 auricles and 2 ventricles).

Physiology: They are homoiothermous. Respiration is by lungs. Double circulation is a characteristic feature of mammals.

Reproduction:

  • Sexes are separate and fertilization is internal.
  • They are viviparous with few exceptions and development is direct.
  • Development is also internal and the foetus is nourished by mother through placenta.