Those Amazing Marsupials From Down Under
By Awake! correspondent in Australia
EXACTLY what is a marsupial, and what makes marsupials amazing?
Put simply, a marsupial is a type of mammal, that is, a warm-blooded animal that suckles its young. Unlike most mammals, however, female marsupials do not form placentas in their womb at the time they become pregnant. They give birth to young that are in a tiny, sightless form, then suckle and protect them in external pouches. So, basically, a marsupial is a mammal with a pouch, for the Latin word marsupium means “pouch” or “pocket.”
Actually, the kangaroo is just one of about 250 species of marsupials. There are marsupials in countries other than Australia—but not many. For example, the North American opossum is a marsupial, and others are found in South America. But by far most of the world’s marsupials are limited to the Australasian region, some 175 different kinds having been identified there. Altogether, there are 45 species of kangaroos in Australia, but the giant red kangaroo is the best known. He is the largest of all marsupials, weighs up to 200 pounds [90 kg], and stands taller than most men. His female mate, though, is noticeably smaller and is bluish-gray in color.
Kangaroos can jump up to 37 feet [11 m] in a single bound. Some have been clocked at speeds of up to 40 miles per hour [64 km/hr] and have jumped over fences more than ten feet [3 m] high. This giant red and the slightly smaller gray kangaroo are found in most parts of the continent down under. They are a common and exciting sight for tourists who drive across semiwooded areas and even over the arid desert regions of central Australia. Kangaroos are gregarious animals and usually stay together in groups called mobs.
A Spectacular Birth
Perhaps the most amazing aspect of marsupial life is the birth and care of the young. Kangaroos are typical of most marsupials. Just 33 to 38 days after mating, baby kangaroo is born. But the new baby is really little more than an embryo—a tiny, bean-shaped creature, weighing about one fiftieth ounce [0.75 gm], smaller than the top of your little finger, and almost transparent.
Immediately after he is born, he “climbs” from his mother’s uterus into her fur. Then, using tiny forearms equipped with claws, he struggles six inches [15 cm] to mother’s pouch. There he attaches himself to one of four teats, which then swells inside his mouth. Through this lifeline, he receives all the nourishment needed, and for the next five months, he remains in this comfortable nursery before poking his head outside for the first time.
At about six months, young joey (as baby kangaroos are called) takes his first tentative step outside, but he often returns to the pouch for nourishment and security. Finally, however, mother decides that joey is too big for the pouch and so prevents him from hopping back inside at all. By the time he is 18 months old, he is completely independent of mother.
Another amazing phenomenon is that mother kangaroo can produce two different types of milk at the same time. Just after the birth of joey number one, she mates again. The newly conceived embryo remains dormant until the first joey begins his brief excursions from the pouch. Then joey number two is born in his tiny form and attaches himself to another teat in the pouch.
But big joey is still taking milk from his original teat. To further complicate matters, the new embryolike joey needs a different milk formula. This is no problem, however, as from his teat, mother is now able to provide high-sugar-content milk, while from big brother’s original teat she continues to provide high-protein and high-fat milk for him!
Although not normally aggressive animals, males sometimes engage in what seem to be boxing matches. Often it is only two younger males testing their strength. At other times two adult males fight by fisticuffs—actually boxing each other over a chosen female! These fights can be quite serious, as the rival suitors claw each other with their forearms and kick violently with their hindlegs.
The Delightful Koala—Another Amazing Marsupial
Almost as well-known as the kangaroo, and featured just as often on Australian tourist brochures, is the cutest marsupial of all—the koala. This little creature is strictly tree-dwelling and moves around mainly at night. He is often confused with a bear because of his appearance, and so he is sometimes erroneously called a koala bear. But he has no relation to the bear family whatsoever, nor is he a kind of opossum or monkey. He is truly unique. Yes, there is only one species of koala, and it is limited to the eastern states of Australia.
The koala has an infinite ability to charm, with its soft, cuddly appearance, bright button eyes, soft rubbery nose, and almost constantly perplexed expression. Not large animals, they grow some two feet [60 cm] in height and weigh from 18 to 30 pounds [8-14 kg].
Baby koala is born like most other marsupials except that mother koala has a backward-opening pouch. The newborn remains in the pouch for six months, and when he finally ventures out, he clings to his mother’s back as she goes about busily searching trees for tasty leaves.
A Unique Digestive System
Koalas are fussy eaters. They limit themselves to the leaves of the eucalyptus tree. And not just any leaf will do. Of the available 600 different species of eucalyptus, koalas eat only 50 or 60. If other animals were to eat these leaves, they would most likely die because of the oil and toxic chemicals in the leaves that are poisonous. A highly complex digestive system helps koalas digest their special food, but such a unique diet does tend to give them a rather distinctive body odor!
Some authorities claim that koalas do not drink water at all, and the word “koala” is purported to be an Aboriginal word meaning “I do not drink.” Yet careful observation has shown that koalas do occasionally come down from their trees to drink, and sometimes they even eat a little soil to augment their mineral-deficient diet.
Although kangaroos can be seen in a number of zoos around the world, koalas are found in very few zoos outside of Australia. But whether you ever have the opportunity personally to see them or not, we feel sure that you will agree that they are truly amazing animals—these mammals with pouches and no placentas.
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Mother kangaroo with joey in pouch
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Koala eating gum leaves
Melbourne Zoo Education Service, Victoria, Australia