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 - Echidnas
The echidna is equipped with horny plates on its tongue and the roof of its mouth, instead of teeth. It crushes termites and ants between these plates. The echidna's tongue is approximately 18cm long.