3 unique characteristics:
- mammary glands (glands that are located on female's breast and can produce milk)
- hair
- three middle ear bones (malleus, incus, and stapes)
Common characteristics:
- All mammals are vertebrates, which means they all have backbones, and all of them have bilateral symmetry. Mammals have the body cavity called Coelom, and it is used to contain all heart and lungs as well as the gut.
- For most mammals, they have the process called gestation, which means their babies develop inside the mother before they are born. Once the babies born, the mother produces milk to feed them.
WARM-BLOODED?
- Most mammals, such as bees, birds and hawk moth, can regulate their temperature, which means they are warm-blooded.
- They can stay active in any weather.
- Other mammals cannot, such as bats and mole rats.