Kangaroo Facts - The Joey Grey Kangaroo With Joey Kangaroo With Joey Wallaby With Joey All marsupials have a pouch in which their young live, drink milk and develop until they are big enough to face the world. The pouches of all macropods open forwards (whereas the pouches of koalas or wombats open backwards). Like all marsupials baby kangaroos are born at a very early stage of development, 31 to 36 days after gestation. If you compare that to humans it would be at the seventh week of a pregnancy. At that stage the joey is not much more than an embryo, a pink hairless tiny worm. Only the front legs are a bit developed, just enough to allow the embryo to make its way into the pouch and attach to one of the four teats. Initially the joey is permanently attached to the teat. As it grows and grows some hairs it also learns to let go and reattach itself. It takes several months until the young is covered in fur, and mature enough to leave the pouch for the first time. In Western Greys for example this takes 9 months! During the following months the joey will spend more and more time outside, exploring its surroundings. Eventually it will permanently leave the pouch. Even after the joey has moved out it will continue to drink milk from the pouch. Weaning takes a few more months. By the time it is fully weaned a grey kangaroo may be over 12 months old! Interesting fact: kangaroos mate again as soon after a joey is borne, but the development of the second embryo stops, or rather, is paused after a few days. So in a way kangaroos are permanently pregnant. If a joey is lost, or if one has grown up and left the pouch, they can immediately give birth again. Even more interesting fact: when kangaroos (after a joey has left the pouch) give birth again, one of their teats will continue to produce a high carbohydrate milk for the older joey. The new baby will attach itself to another teat that produces a different kind of milk with a higher fat content. Pretty amazing... A female kangaroo can have three babies at the same time: an older joey living outside the pouch but still drinking milk, a young one in the pouch attached to a teat, and an embryo awaiting birth. Because of this very efficient way of bringing up their young, kangaroos raise on average three young every two years, even though it takes such a long time for the joey to become independent......
Posted on: Thu, 10 Jul 2014 04:18:27 +0000