On Mothers Day, the National Geographic Channel will be featuring the latest episode of the In the Womb series called Extreme Animals.
The red kangaroo is another animal of extremes. Like all marsupials, the embryo of the kangaroo spends only a short time in the actual womb. At the age of four weeks when the joey is only the size of a jelly bean, a journey begins from the womb to the pouch. At this stage the joey has fully developed forelimbs, but the hind limbs are just stumps. It makes the 12″ journey up to the pouch and immediately latches on to the nipple. It will not stop suckling for the next six months. The properties of the milk change to suit each stage of growth. At ten weeks the joey is mouse sized–by 6 months it will be the size of a squirrel By 7 months it will choose when to feed and it will begin to experience the world outside the pouch. By nine months the joey will leave the pouch.
An interesting fact is that, should this joey die at any stage, another ‘back-up’ embryo will break out of dormancy and take its place. Called embryonic diapause, this may be a strategy to increase chances for survival during times of environmental stress.
See In the Womb: Extreme Animals Sunday at 7 PM on the National Geographic Channel. (Check your local listings for the time in your region)
Image courtesy of National Geographic.