Kangaroo . Animal belonging to the Macropodidae family. It is one of the first animals that children learn to know and yet, being known all over the world, it still keeps many enigmas for science.
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- 1 Geographical location
- 2 Origin of the name
- 3 Origin and evolution
- 1 From America to Australia
- 2 From the jungle to the desert
- 4 General characteristics
- 5 real kangaroos
- 6 Species of the genus Macropus
- 7 Playback
- 8 Natural environment
- 9 Food
- 10 Sources
All of them are only found in the Australian continent and New Guinea, where you can see these animals crossing the harsh deserts, hiding in the rocky areas or climbing the trees of the jungle.
The word kangaroo derives from the term “gangurru” , a word from the Guugu Yimidhirr (Australian aboriginal language), which means “gray kangaroo”. The name was written for the first time (in its English version, “kangaroo”), by Lieutenant James Cook, on August 4 , 1770 .
A widespread legend affirms that in reality the name kangaroo would have arisen when the Westerners asked the name of that animal and this is what the aborigines answered; its meaning, however, was not the name of the animal, but the phrase “I don’t understand him.”
Origin and evolution
From America to Australia
The history of marsupials dates back to about 130 million years ago (in the Lower Cretaceous), when they separated from the rest of the mammals in North America ; thereafter, they evolved completely independently. During the Upper Cretaceous it reached its maximum splendor in the same area, and only at the end of that time (about 70 million years ago) did they emigrate to South America , while they practically disappeared from North America.
Thus, in the Paleocene (about 60 million years ago) they occupied all of South America and crossing Antarctica , they reached the Australian continent. At that time, America , Antarctica and Australia were united.
During much of the Miocene (between 25 and 5 million years ago), Australia was covered almost entirely by tropical forest, which slowly receded towards the edges of the continent (today only small strips remain in the northeast, and in some points these lands are only 50 km wide.
From the jungle to the desert
Australian marsupials lived, evolved, and diversified in the rainforest for a long time. They were surely good climbers; They possessed a prehensile tail and long toes on their feet with sharp nails.
About 15 million years ago, the ancestors of today’s kangaroos left the trees, perhaps in search of food more nutritious than leaves. This brought with it a series of modifications to adapt to life on Earth. Furthermore, their physiology had to be made compatible with life in arid climates, environments that were then beginning to predominate in Australia. Finally, the desert landscapes became dominant and in their immensity, the kangaroos were diversifying, originating the more than fifty current species.
They have a heavy body, small front legs and long back legs, with incredible strength. They also have a long and muscular tail. Females have an incubator bag.
There are many groups of marsupials (about 260 species grouped in about twenty families), all of them related to a greater or lesser extent with kangaroos. However, the so-called “true kangaroos” are only those that belong to the macropodid family. This includes 10-11 genera and around fifty species.
Species of the genus Macropus
- Euro ( Macropus robustus)
- Giant kangaroo ( Macropus giganteus)
- Gray Kangaroo ( Macropus futiginosus)
- Kangaroo ualaru antilopito ( Macropus antilopinus)
- Black wallaru ( Macropus bernardus)
- Whip-tailed wallaby( Macropus parryl )
- Black-banded wallaby( Macropus dorsalis )
- Western wallaby( Macropus irma )
- Tammar wallaby ( Macropus eugenii)
- Wallaby parma ( Macropus parma)
- Marsh wallaby( Macropus bicolor )
- Red-necked wallaby( Macroous rufogriseus )
- Agile wallaby (Macropus agilis)
- Rock wallaby (genus Petrogale)
- Northern pointed-tailed wallaby( Onychogalea unguifera )
- Matschie Tree Kangaroo ( Dendrolagus matschiei – goodfellowi)
Their reproduction is sexual and varies greatly with the species. The red kangaroo is an opportunistic breeder, as it mates and reproduces when seasonal conditions are favorable for raising young. Gray kangaroos breed throughout the year, but give birth to more young in the summer months, as they come out of the pouch at the ideal time: spring. Other species have a more restricted breeding season.
The courtship can last a few hours or last 2 or 3 days. The male follows the female in heat, frequently sniffing the opening of the urogenital sac and touching the female’s tail with his paw. The male wallaby makes characteristic lateral and sinuous movements with the tail, which produce clicking sounds; mating can be brief or last more than an hour, as in the case of the gray kangaroo.
In many species, such as the cuoca, mating takes place after parturition; in these cases, a resting blastocyst is usually produced, which develops later, when the young from the previous parturition leaves the pouch. The young are born between 28 and 36 days after mating, being still very underdeveloped, hairless and with the eyes and ears still embryonic and without function.
Female red kangaroos, weighing about 27 kg, give birth to a calf weighing just 800 milligrams. The delivery is fast, and as soon as it is free the baby begins to advance towards the breast, moving its head from side to side, crawling along the mother’s womb, and once inside the pouch, it firmly takes the breast in its mouth and the end of it is dilated to fill the oral cavity.
The whole process takes place in a few minutes. They remain in the bag for about 8 months, but they keep coming back to suckle for about six more months; in that time another baby will have been born. Young people often associate with their mothers until they reach sexual maturity. Usually only one calf is born, but twins have been reported.
Kangaroos are restricted to the area of Australia, Tasmania, New Guinea and neighboring islands. Specifically, the red kangaroo occupies a large area of distribution, surpassed only by that of the so-called euro or ualaru (wallarao). Both can be found in about 70% of the territory of Australia. Likewise, they are the only ones who live in the immense arid zone of the interior of the continent. The other species occupy coastal strips of greater or lesser amplitude. The red kangaroo is only missing from the northern and eastern coastal strip, as well as the extreme south-west.
Kangaroos inhabit dry forests, weeds, grasslands, savannas, steppes and arid plains, and even deserts. Although most live in similar environments, the one that most supports dry areas without water is the red kangaroo, equaled only by the euro. As long as they have green grass, they can go without drinking indefinitely. This allows it to occupy absolutely arid lands – almost devoid of animal life – with little competition.
All kangaroos eat vegetables, leaves, or preferably grass. The most primitive species tend to browse, while the more modern ones tend to graze. Thus, the red kangaroo is herbivorous. One of the activities that kangaroos usually do in a group is feeding. In this way, they are safer if a predator approaches. At the slightest danger, the sudden movement of one of them can trigger the flight of the entire group.
The red kangaroo cuts the grass with the three upper incisors, which it applies on the lower ones and chews the plants very well so as not to have to regurgitate and ruminate them, as happens in more evolved species. For this reason, the sixteen molars wear a lot, so they have a continuous forward advance and are renewed up to four times. The stomach is very different from that of ruminants: it is lined with cells that secrete a liquid rich in bacteria, whose enzymatic secretion facilitates the digestive process by degrading cellulose. Very bulky, when the stomach is full it can constitute 15% of the weight of the animal.
The kangaroo is adapted to desert settings, but this does not mean that it despises water when it is available; in a few minutes you can drink up to 10% of your own weight. If you can’t find water, you avoid dehydration as much as possible; It is most active at night, taking refuge in the shade and licking its skin in parts of the body where blood circulates near the surface. He also eats a mixture of plants and roots that helps prevent dehydration.