Kangaroo - Birth and Infancy

2 Min
Created at 10 / 2012
9.8
9.6   Informative
10.0   Entertaining
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By Nat Geo WILD
121 Videos
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The Australian kangaroo as a marsupial

One of the strangest and most fascinating birthing processes in the animal kingdom is that of the Australian grey kangaroo. Like possums, koalas, wombats and wallabies, kangaroos are marsupials that are found mainly in Australia. Marsupials represent about 6% of all mammals, and their most unique characteristic is that they all give birth to undeveloped offspring who spend time inside of their mother’s pouch until they are fully developed and ready to go out into the world. This video displays exactly what occurs during the kangaroo’s birthing process.

After the egg descends from the ovary and into the uterus, if the female kangaroo finds herself pregnant then the neonate will take about 33 days to develop inside the uterus. Once the 33 days are over, the female kangaroo is ready to give birth to the kangaroo baby; she will usually give birth to only one baby at a time. From this point on, the baby kangaroo is called a joey.

Kangaroo delivery process

The kangaroo’s delivery process is very gentle, in order to account for the still-undeveloped state of the newborn, who is born approximately the size of a jellybean and weighs only two grams. The joey is born blind, hairless and with undeveloped back legs, organs and central nervous system. It instinctively uses its sense of smell and forelegs to make its way out of one of the mother’s two uteri and into her pouch by climbing through her thick fur. This process takes the baby joey about three to five minutes to complete.  

Once the joey makes its way into the pouch, the mother’s sexual cycle restarts almost immediately. A second egg descends from the ovary and into the uterus and she becomes sexually receptive. However, if she does mate and the egg becomes fertilized, the process will be temporarily put on hold in order to allow for the first joey to grow to maturity.

What happens inside the kangaroo’s pouch?

Meanwhile, inside the mother’s pouch, the joey latches onto one of the mother’s teats and begins feeding. The baby joey receives vital nutrients from the mother’s milk, allowing for it to properly grow and develop. After about 190 days the joey is ready to leave the mother’s pouch for the first time. From that point on, the little kangaroo will spend more and more time outside of the pouch, but will come back if it senses danger or is in need of protection.

As the joey begins spending time outside of it’s mother’s pouch, the mother’s body begins preparing for the next baby. Her body will begin to develop the fertilized egg that has been waiting in her womb, and after 33 days a second joey will find it’s way into the mother’s pouch. The second joey will begin to suckle from a different one of the mother’s teats than the first joey. Remarkably, the mother kangaroo’s mammary glands are able to produce two different types of milk at the same time. Each type of milk is made of a different chemical composition. This allows for the older joey to indulge in milk with a much higher fat content than that of the younger joey, enabling both joeys to receive suitable and proper nourishment, according to their respective needs.

The little kangaroos’ life outside of the pouch

Approximately 235 days later the mature joey will be completely ready leave the pouch for good, leaving the mother room to carry her next baby. However, shortly after leaving the pouch, the mother will stay close to the little joey and not let it stray away too far. Eventually, the joey will become independent of its mother and learn to be a part of the mob.  After the kangaroo is off on its own, its lifespan can range between six and 20 years, depending on its living conditions. Most kangaroos in the wild, however, do not have a long lifespan. 

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