Together with wallabies and wallaroos, kangaroos comprise the family Macropodidae which also includes the rat-kangarooos, hare-wallabies, tree-kangaroos, pademelons, the quokka and the euro.
The kangaroo's ancestors were tree dwellers with prehensile tails and toes adapted for grasping branches in a similar manner to possums. As they came to ground and took to grazing and hopping, they gradually increased in size and developed elongated hind limbs which made their forelimbs appear undeveloped.
The tail also became elongated for use as a counterbalance when hopping and as a prop when grazing. A change of diet brought about a change in the structure of the kangaroo's teeth and digestive organs. The various species differ mainly in size and are classified according to the structure of the teeth rather than outward appearance so that it is difficult for a lay person to identify a particular species of kangaroo.
Kangaroos vary in size from the small rat kangaroo which has a body length of about 30 cm to the great grey kangaroo which may stand over 2 meters tall. Colours range through various shades of grey and brown and some have bands of stripes on the lower back and tail.
All kangaroos are herbivorous except for the rat-kangaroo, which feeds on insects and their larvae, worms, fruit and grass roots. This diet is thought to account for their strong musk odor.
Larger species such as the grey or red kangaroos are strong, speedy and agile and can reach a speed of 48 km per hour in leaps averaging 11 meters. Tree kangaroos are not agile on the ground but can make huge leaps from trees, sometimes as far as 18 meters.
Being marsupials, kangaroos carry their young in a pouch. When first born the young are only a few centimetres long and extremely immature. However, they make their way unassisted from the birth canal to the pouch where they attach themselves to a teat which swells to hold them securely in place. Early settlers, observing this, came to the conclusion that the young somehow grew from the mother's teats.
When Captain James Cook first saw animals 'of a light mouse colour and the full size of a grey hound ... jumping seven or eight feet at each hop upon its hind legs only', he was told by the aborigines that they were kangaroos, or kangurus - the first Aborigine word to be used in the English language.
The kangaroo is the dominant native animal of Australia and is found now here else in the world except for Papua New Guinea and a few neighbouring islands. It is generally a harmless, docile animal but if cornered will sometimes balance on its tail and rake the enemy with the nails on its hind feet. As captives in zoos or sanctuaries they become very tame and can be hand fed and fondled.
In the wild kangaroos sometimes become so numerous that they are regarded by farmers as a menace. Officers of the State National Parks and Wildlife Services then grant shooters' licences to kill a controlled number. The hides are used in the manufacture of purses, wallets and toy koala bears for children, and the meat is used in the production of pet food.
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