Groups of kangaroos are called 'mobs'
When a kangaroo is moving slowly the tail is used as an extra leg and supports the kangaroo when it is standing on its hind legs. Most kangaroos can only move both back legs together and not one at a time.
Kangaroos have good eyesight but only respond to moving objects. They have excellent hearing and can swivel their large ears in all directions to pick up sounds. Kangaroos are social animals that live in groups or "mobs" of at least two or three individuals and up to 100 kangaroos.