Mammals are the highest class of vertebrates and the female has mammary glands which secrete milk for the nourishment of young after birth. Mammals are warm-blooded and the majority of their body is covered with hair. Mammals give birth to live young (except the platypus and echidna, who lay eggs). They also have three middle ear bones.
Most mammals live solely on land, but there are several groups that have specifically evolved to exist solely in aquatic environments (dolphins and whales) one of which is the largest of all animals. Only one group has mastered the art of true flight (bats) although several have developed the ability to glide through tree tops.
Our Amazing Mammals
ANIMAL FACTS - Kangaroos
The dominant male kangaroo is under constant challenges from other mature males within the mob. This ensures the strongest, fittest male remains as the primary breeder and passes the best genes on to the next generation.