A Kangaroo is a marsupial mammal, which means its babies are born incompletely developed and are typically carried and suckled in a pouch on the mother's belly. A female kangaroo is called a flyer. A male kangaroo is called a boomer. It is a macropod which means "big foot". There are over 40 different types (species) of Kangaroo. The smaller ones are usually called Wallabies. A baby kangaroo is called a joey.
There are 65 kangaroo species – ranging from the small tree-kangaroo to the red giant kangaroo, which is the largest of all. When it stands upright, it is as tall as an adult human.