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KANGAROO,
common name for any of about 54 species of MARSUPIAL animals constituting
the family Macropodidae, found in Australia and neighboring islands.
Typical large kangaroos have sheeplike heads; large, movable ears;
slender chests; and heavy hind parts. They have short front legs with
five unequal digits, and long, powerful hind legs with tendons that
act like springs for energy-efficient hopping. A large kangaroo
can cover a distance of 6.6 m (25 ft) in a single leap. The hind
feet typically have four toes; the toe adjacent to the outside digit
bears a long, sharp claw used in defense. (A large kangaroo, although
ordinarily timid, is dangerous when at bay, pummeling its attacker
with its forepaws and slashing with its powerful hind legs.) The
long, muscular tail is used as a support when the animal sits or
walks, and for balance when it leaps. The tough hide is often covered
with soft, woolly fur. Kangaroo hunting, for their hide and flesh,
has been a popular sport in Australia, with hundreds of thousands
killed each year.
Female kangaroos, like the females of other marsupials, have
special abdominal pouches. The newly born young, commonly called
a joey, finds its way into the pouch by following a path of fur
that the mother’s tongue has moistened. The pouch, in which
the joey is kept until it is 5 to 9 months old (depending on species),
contains four mammary glands, of which two at a time are functional.
The joey emerges permanently at from 6 to 10 months, and then stays
with its mother, continuing to suckle by placing its head in her
pouch, usually until it is 12 to 18 months old.
The best known and largest species of kangaroo are the giant,
or great gray, kangaroo, Macropus giganteus, and
the red, or woolly, kangaroo, M. rufus. Both species
reach a body length of slightly more than 1.5 m (about 5 ft), exclusive
of the tail, which is 1.2 to 1.3 m (4 to 4.5 ft) long. M. robustus, a
somewhat stouter species, is known as the wallaroo. Large kangaroos
are terrestrial grazing animals that subsist chiefly on vegetation.
Sheep ranchers have claimed that the animals damage grazing lands,
but such overgrazing can sometimes be attributed to the sheep themselves.
Kangaroos of smaller size, commonly called wallabies, are
usually brighter in color than the large species. Many of these
species are about the size of a rabbit; those of the genus Lagorchestes, in
particular, so resemble rabbits that they are called hare wallabies.
Similar species in the genus Onychogalea are called
nail-tailed wallabies because their tails are tipped with a horny
nail. The genus Thylogale contains the relatively
short-tailed pademelons. The rednecked wallaby, Macrophus
rufogriseus, inhabits thickets, whereas the rock wallabies
of the genus Petrogale live in crevices in rocks.
Unlike most other kangaroos, the rock wallabies are chiefly nocturnal.
The only arboreal kangaroos are the small tree kangaroos of the
genus Dendrolagus, whose front legs are almost
as long as their hindlegs. These marsupials are inefficient in making
their way either on the ground or in trees, but they prefer an arboreal
habitat.
The potoroos, or “rat” kangaroos, are small
members of the family that form a subfamily by themselves. The animals
resemble jumping mice. Many of the species, although terrestrial,
have a prehensile tail. The best-known genera are Potorous, containing
the typical rat kangaroo; and Bettongia, containing
the short-nosed rat kangaroo.
The musk kangaroo, Hypsiprymnodon moschatus, is
a ratlike wallaby living in the rain forest of northern coastal
Queensland. It differs in having five toes on each hind foot and
in having an almost completely naked and scaly tail. This animal
may be a link between the kangaroo and the related PHALANGER.