Red kangaroo has the ability to freeze the development of an embryo until the previous joey is able to leave the pouch. This is known as diapause, and will occur in times of drought and in areas with poor food sources. The composition of the milk produced by the mother varies according to the needs of the joey. In addition, red kangaroo mothers may "have up to three generations of offspring simultaneously; a young-at-foot suckling from an elongated teat, a young in the pouch attached to a second teat and a blastula in arrested development in the uterus". The kangaroo has also
Kangaroo female kangaroos have a pouch called a marsupium in which joeys complete postnatal development. The large kangaroos have adapted much better than the smaller macropods to land clearing for pastoral agriculture and habitat changes brought to the Australian landscape by humans. Many of the smaller species are rare and endangered, while kangaroos are relatively plentiful. The kangaroo is a symbol of Australia and appears on the Australian coat of arms and on some of its currency and is used by some of Australia's well known organisations, including Qantas and the Royal Australian Air Force. The kangaroo is important to both