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Kangaroo

2007 Schools Wikipedia Selection. Related subjects: Mammals

       How to read a taxoboxKangaroos
   Female Eastern Grey Kangaroo with joey
   Female Eastern Grey Kangaroo with joey
         Scientific classification

   Kingdom:  Animalia
   Phylum:   Chordata
   Class:    Mammalia
   Subclass: Marsupialia
   Order:    Diprotodontia
   Suborder: Macropodiformes
   Family:   Macropodidae
   Genus:    Macropus
             in part

                                   Species

   Macropus rufus
   Macropus giganteus
   Macropus fuliginosus
   Macropus antilopinus

   A kangaroo is a marsupial from the family Macropodidae. In common use
   the term is used to describe the largest species from this family, the
   Red Kangaroo, the Antilopine Kangaroo, and the Eastern and Western Grey
   Kangaroo of the Macropus genus. The family also includes many smaller
   species which include the wallabies, tree-kangaroos, wallaroos,
   pademelons and the Quokka, some 63 living species in all. Kangaroos are
   endemic to the continent of Australia, while the smaller macropods are
   found in Australia and New Guinea.

   In general, larger kangaroos have adapted much better to changes
   wrought to the Australian landscape by humans, as many of their smaller
   cousins are endangered. However there is considerable controversy over
   farming of kangaroos for meat.

   The kangaroo is an Australian icon: it is featured on the Australian
   Coat of Arms, on some currency, and is used by many Australian
   organizations, including Qantas.

Terminology

   The word kangaroo derives from the Guugu Yimidhirr word gangurru,
   referring to a grey kangaroo. The name was first recorded as "Kangooroo
   or Kanguru" on 4 August 1770, by Lieutenant (later Captain) James Cook
   on the banks of the Endeavour River at the site of modern Cooktown,
   when HM Bark Endeavour was beached for almost seven weeks to repair
   damage sustained on the Great Barrier Reef.

   Kangaroo soon became adopted into standard English where it has come to
   mean any member of the family of kangaroos and wallabies. Male
   kangaroos are called bucks, boomers, jacks, or old men; females are
   does, flyers, or jills, and the young ones are joeys. The collective
   noun for kangaroos is a mob, troop, or court. Kangaroos are sometimes
   colloquially referred to as roos.

Overview

   A Tasmanian Forester (Eastern Grey) Kangaroo in motion.
   A Tasmanian Forester ( Eastern Grey) Kangaroo in motion.

   There are four species that are commonly referred to as kangaroos:
     * The Red Kangaroo (Macropus rufus) is the largest surviving
       marsupial anywhere in the world. Fewer in numbers, the Red Kangaroo
       occupies the arid and semi-arid centre of the continent. A large
       male can be 2 metres (6 ft 7 in) tall and weigh 90 kg (200 lb).
     * The Eastern Grey Kangaroo (Macropus giganteus) is less well-known
       than the red (outside of Australia), but the most often seen, as
       its range covers the fertile eastern part of the continent.
     * The Western Grey Kangaroo (Macropus fuliginosus) is slightly
       smaller again at about 54 kg (119 lb) for a large male. It is found
       in the southern part of Western Australia, South Australia near the
       coast, and the Darling River basin.
     * The Antilopine Kangaroo (Macropus antilopinus) is, essentially, the
       far-northern equivalent of the Eastern and Western Grey Kangaroos.
       Like them, it is a creature of the grassy plains and woodlands, and
       gregarious.

   In addition, there are about 50 smaller macropods closely related to
   the kangaroo in the family Macropodidae.

Description

   Red Kangaroo (Macropus rufus)
   Red Kangaroo (Macropus rufus)

   Kangaroos have long been regarded as strange animals. Early explorers
   described them as creatures that had heads like deer (without antlers),
   stood upright like men, and hopped like frogs. Combined with the
   two-headed appearance of a mother kangaroo, this led many back home to
   dismiss them as travellers tales for quite some time.

   Kangaroos have large, powerful hind legs, large feet adapted for
   leaping, a long muscular tail for balance, and a small head. Like all
   marsupials, kangaroos have a pouch called a marsupium in which joeys
   complete postnatal development.

Behaviour

   Kangaroos are the only large animals to use hopping as a means of
   locomotion. The comfortable hopping speed for Red Kangaroo is about
   20–25 km/h (13–16 mph), but speeds of up to 70 km/h (44 mph) can be
   attained, over short distances, while it can sustain a speed of 40 km/h
   (25 mph) for more than a mile. This fast and energy-efficient method of
   travel has evolved because of the need to regularly cover large
   distances in search of food and water, rather than the need to escape
   predators.

   Because of its long feet, it cannot walk normally. To move at slow
   speeds, it uses its tail to form a tripod with its two forelimbs. It
   then raises its hind feet forward, in a form of locomotion called
   "crawl-walking."

   The average life expectancy of a kangaroo is about 4–6 years, with some
   living until they are about 23.

Diet

   Kangaroos are large herbivores, feeding on grass and roots, and they
   chew cud. Many species are nocturnal and crepuscular, usually spending
   the days idling quietly and the cool evenings, nights and mornings
   moving about and feeding, typically in packs.

   Because of its grazing, the kangaroo has developed specialized teeth.
   Its incisors are able to crop grass close to the ground, and its molars
   chop and grind the grass. Since the two sides of the lower jaw are not
   joined together, the lower incisors are farther apart, giving the
   kangaroo a wider bite. The silica in grass is abrasive, so kangaroo
   molars move forward as they are ground down, and eventually fall out,
   replaced by new teeth that grow in the back.

   Different kangaroos also prefer different diets. The Red Kangaroo
   prefers dry grasses to juicy plants, because juicy grasses are very
   bulky, and the water inside takes too much space. The two gray kangaroo
   species, however, prefer soft, fresher grasses, as it is a woodland
   animal, opposed to the desert environment of the Red Kangaroo.

   In dry weather, all kangaroos hold food in their digestive system for a
   longer period of time to absorb the last bits of moisture. However,
   gray kangaroos are more prone to dehydration, because they do not have
   much need to conserve water in their woodland habitat.

Predators

   Kangaroos have few natural predators. The Thylacine, considered by
   palaeontologists to have once been a major natural predator of the
   kangaroo, is now extinct. Other extinct predators included the
   Marsupial Lion, Megalania and the Wonambi. However, with the arrival of
   humans in Australia at least 50,000 years ago and the introduction of
   the dingo about 5,000 years ago, kangaroos have had to adapt. The mere
   barking of a dog can set a full-grown male boomer into a wild frenzy.
   Wedge-tailed Eagles and other raptors usually eat kangaroo carrion.
   Goannas and other carnivorous reptiles also pose a danger to smaller
   kangaroo species when other food sources are lacking.

   Along with dingoes and other canids, introduced species like foxes and
   feral cats also pose a threat to kangaroo populations. Kangaroos and
   wallabies are adept swimmers, and often flee into waterways if
   presented with the option. If pursued into the water, a large kangaroo
   may use its forepaws to hold the predator underwater so as to drown it.
   Another defensive tactic described by witnesses is catching the
   attacking dog with the forepaws and disembowelling it with the hind
   legs.

Adaptations

   Newborn joey sucking on a teat in the pouch
   Newborn joey sucking on a teat in the pouch

   Kangaroos have developed a number of adaptations to a dry, infertile
   continent and highly variable climate. As with all marsupials, the
   young are born at a very early stage of development – after a gestation
   of 31–36 days. At this stage, only the forelimbs are somewhat
   developed, to allow the newborn to climb to the pouch and attach to a
   teat. In comparison, a human embryo at a similar stage of development
   would be about seven weeks old, and premature babies born at less than
   23 weeks are usually not mature enough to survive. The joey will
   usually stay in the pouch for about nine months (180–320 days for the
   Western Grey) before starting to leave the pouch for small periods of
   time. It is usually fed by its mother until reaching 18 months.

   The female kangaroo is usually pregnant in permanence, except on the
   day she gives birth; however, she 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, the mother is able to produce two different kinds of milk
   simultaneously for the newborn and the older joey still in the pouch.

   Unusually, during a dry period, males will not produce sperm, and
   females will only conceive if there has been enough rain to produce a
   large quantity of green vegetation.

   Kangaroos and wallabies have large, stretchy tendons in their hind
   legs. They store elastic strain energy in the tendons of their large
   hind legs, providing most of the energy required for each hop by the
   spring action of the tendons rather than by any muscular effort. This
   is true in all animal species which have muscles connected to their
   skeleton through elastic elements such as tendons, but the effect is
   more pronounced in kangaroos.

   There is also a link between the hopping action and breathing: as the
   feet leave the ground, air is expelled from the lungs; bringing the
   feet forward ready for landing refills the lungs, providing further
   energy efficiency. Studies of kangaroos and wallabies have demonstrated
   that, beyond the minimum energy expenditure required to hop at all,
   increased speed requires very little extra effort (much less than the
   same speed increase in, say, a horse, dog or human), and that the extra
   energy is required to carry extra weight. For kangaroos, the key
   benefit of hopping is not speed to escape predators—the top speed of a
   kangaroo is no higher than that of a similarly-sized quadruped, and the
   Australian native predators are in any case less fearsome than those of
   other continents—but economy: in an infertile continent with highly
   variable weather patterns, the ability of a kangaroo to travel long
   distances at moderately high speed in search of food sources is crucial
   to survival.

   A sequencing project of the Kangaroo genome was started in 2004 as a
   collaboration between Australia (mainly funded by the state of
   Victoria) and the National Institutes of Health in the US. The genome
   of a marsupial such as the kangaroo is of great interest to scientists
   studying comparative genomics because marsupials are at an ideal degree
   of evolutionary divergence from humans: mice are too close and haven't
   developed many different functions, while birds are genetically too
   remote. The dairy industry has also expressed some interest in this
   project.

Kangaroo blindness

   Eye disease is rare but not new among kangaroos. The first official
   report of kangaroo blindness took place in 1994, in central New South
   Wales. The following year, reports of blind kangaroos appeared in
   Victoria and South Australia. By 1996, the disease had spread "across
   the desert to western Australia". Australian authorities were concerned
   that the disease could spread to other livestock and possibly humans.
   Researchers at the Australian Animal Health Laboratories in Geelong
   detected a virus called the Wallal virus in two species of midge,
   believed to have been the carriers. Veterinarians also discovered that
   less than three percent of kangaroos exposed to the virus developed
   blindness.

Interaction with humans

   Before European settlement, the kangaroo was a very important animal
   for Australian Aborigines, for its meat, hide, bones and sinews. In
   addition, there were important Dreaming stories and ceremonies
   involving the kangaroo. Aherrenge is a current kangaroo dreaming site
   in the Northern Territory. The game of Marn grook was played using a
   ball made from kangaroo by the Kurnai people.

   Unlike many of the smaller macropods, kangaroos have fared well since
   European settlement. European settlers cut down forests to create vast
   grasslands for sheep and cattle grazing, added stock watering points in
   arid areas, and have substantially reduced the number of dingoes.

   Kangaroos are shy and retiring by nature, and in normal circumstances
   present no threat to humans. Male kangaroos often "box" amongst each
   other, playfully, for dominance, or in competition for mates. The
   dexterity of their forepaws is utilised in both punching and grappling
   with the foe, but the real danger lies in a serious kick with the
   hindleg. The sharpened toenails can disembowel an opponent.

   There are very few records of kangaroos attacking humans without
   provocation, however several such unprovoked attacks in 2004 spurred
   fears of a rabies-like disease possibly affecting the marsupials. The
   only reliably documented case of a fatality from a kangaroo attack
   occurred in New South Wales, in 1936. A hunter was killed when he tried
   to rescue his two dogs from a heated fray. Other suggested causes for
   erratic and dangerous kangaroo behaviour include extreme thirst and
   hunger.

   In 2004, Lulu, an Eastern Grey, saved a farmer's life. She received the
   RSPCA National Animal Valor Award on May 19 of that year.

Conflict with vehicles

   A "kangaroo crossing" sign on an Australian highway.
   A "kangaroo crossing" sign on an Australian highway.
   A kangaroo crossing a highway.
   A kangaroo crossing a highway.

   A collision with a vehicle is capable of killing a kangaroo. Kangaroos
   blinded by headlights or startled by engine noise have been known to
   leap in front of cars. Since kangaroos in mid-bound can reach speeds of
   around 50 km/h (31 mph) and are relatively heavy, the force of impact
   can be severe. Small vehicles may be destroyed, while larger vehicles
   may suffer engine damage. The risk of harm to vehicle occupants is
   greatly increased if the windscreen is the point of impact. As a
   result, "kangaroo crossing" signs are commonplace in Australia.

   Vehicles that frequent isolated roads, where roadside assistance may be
   scarce, are often fitted with " roo bars" to minimise damage caused by
   collision. Bonnet-mounted devices, designed to scare wildlife off the
   road with ultrasound and other methods, have been devised and marketed.

   If a female is the victim of a collision, animal welfare groups ask
   that her pouch be checked for any surviving joey, in which case it may
   be removed to a wildlife sanctuary or veterinary surgeon for
   rehabilitation. Likewise, when an adult kangaroo is injured in a
   collision, a vet, the RSPCA or the National Parks and Wildlife Service
   can be consulted for instructions on proper care. In New South Wales,
   rehabilitation of kangaroos is carried out by volunteers from WIRES.

Hand-raising

   Occasionally, individuals take on the task of rearing a recovered joey
   themselves. The rule-of-thumb says that if the joey is already covered
   with fur at the time of the accident (as opposed to still being in its
   embryonic stage), it stands a good chance of growing up properly.
   Lactose-free milk is required, otherwise the animal may develop
   blindness. They hop readily into a cloth bag when it is lowered in
   front of them approximately to the height where the mother's pouch
   would be. The joey's instinct is to "cuddle up", thereby endearing
   themselves to their keepers, but after hand-rearing a joey, it cannot
   usually be released into the wild and be expected to provide for itself
   immediately. Usually wildlife sanctuaries are willing to adopt
   kangaroos which are no longer practical, or have grown too large to
   contain, needing at least 1 acre and 7ft boundary fences for a fully
   grown kangaroo.
   Retrieved from " http://en.wikipedia.org/wiki/Kangaroo"
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   with only minor checks and changes (see www.wikipedia.org for details
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