Kangaroos are four marsupials from the family Macropodidae, noted for hopping and bouncing on their hind legs. some of which are called wallabies.
The Macropodidae are found in Australia (including Tasmania and other offshore islands, such as Kangaroo Island), New Guinea, and the islands east to the Bismarck Archipelago. Several species have been introduced into New Zealand.
Kangaroos have large, powerful hind legs, large feet adapted for leaping, a long muscular tail for balance, and a small head. Like most marsupials, female kangaroos have a pouch called a marsupium in which joeys’ complete postnatal development takes place. All members of the kangaroo family rely on long, powerful hind legs and feet for hopping and leaping, their predominant forms of locomotion.
Their long tails, thickened at the base, are used for balancing. This feature is most obvious in the large kangaroos, which use the tail as a third leg when standing still. Each long, narrow hind foot has four toes, the large fourth toe bearing most of the animal’s weight. The second and third toes are united.
The short forelimbs, having five unequal digits, are used almost like human arms, but all digits of the “hand” are sharp-clawed, and the thumb is not opposable.
The mouth is small, with prominent lips. All macropodids are herbivorous and have a chambered stomach that is functionally similar to those of such ruminants as cattle and sheep. Because of its grazing habits, the kangaroo has developed specialised teeth that are rare among mammals. Its incisors can 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 or fused, the lower incisors are farther apart, giving the kangaroo a wider bite. The silica in the grass is abrasive, so kangaroo molars are ground down and they actually move forward in the mouth before they eventually fall out, and are replaced by new teeth that grow in the back.
Groups of kangaroos are called mobs, courts or troupes, which usually have 10 or more kangaroos in them. Living in mobs can provide protection for some of the weaker members of the group. The size and stability of mobs vary between geographic regions. One common behaviour is nose touching and sniffing, which mostly occurs when an individual joins a group. The kangaroo performing the sniffing gains much information from smell cues. This behaviour enforces social cohesion without consequent aggression. During mutual sniffing, if one kangaroo is smaller, it will hold its body closer to the ground and its head will quiver, which serves as a possible form of submission.
Greetings between males and females are common, with larger males being the most involved in meeting females. The sexual activity of kangaroos consists of consort pairs. Oestrous females roam widely and attract the attention of males with conspicuous signals. A male will monitor a female and follow her every movement. He sniffs her urine to see if she is in oestrus. The male will then proceed to approach her slowly to avoid alarming her. If the female does not run away, the male will continue by licking, pawing, and scratching her, and copulation will follow. After the copulation is over, the male will move on to another female. Consort pairing may take several days and the copulation is also long. Thus, a consort pair is likely to attract the attention of a rival male. As larger males are tending bond with females near oestrus, smaller males will tend to females that are farther from oestrus. Dominant males can avoid having to sort through females to determine their reproductive status by searching for tending bonds held by the largest male they can displace without a fight.
In all species, the marsupium (or pouch) is well developed, opens forward, and contains four teats. The young kangaroo (“joey”) is born at a very immature stage when it is only about 2 cm (1 inch) long and weighs less than a gram.
Immediately after birth, it uses its already clawed and well-developed forelimbs to crawl up the mother’s body and enter the pouch. The joey attaches its mouth to a teat, which then enlarges and holds the young animal in place. After continuous attachment for several weeks, the joey becomes more active and gradually spends more and more time outside the pouch, which it leaves completely at 7 to 10 months of age.
The kangaroo along with the koala are symbols of Australia. A kangaroo appears on the Australian coat of arms and some of its currency, and is used as a logo for some of Australia’s most well-known organizations,
The kangaroo is important to both Australian culture and the national image, and consequently, there are numerous popular cultural references.
The kangaroo appears in Rudyard Kipling’s Just So Stories, “The Sing-Song of Old Man Kangaroo,” while the kangaroo is chased by a dingo, he gives Nqong the Big God’s advice, that his legs and tail grew longest before five o’clock.
The kangaroo and wallaby feature predominantly in Australian sports teams’ names and mascots. Examples include the Australian national rugby league team (the Kangaroos) and the Australian national rugby union team (the Wallabies).
Kangaroos are well-represented in films, television, books, toys and souvenirs around the world. Skippy the Bush Kangaroo was a popular 1960s Australian children’s television series about a fictional pet kangaroo. Kangaroos are featured in the Rolf Harris song “Tie Me Kangaroo Down, Sport” and several Christmas carols.
