Many people know that the kangaroo is a marsupial from the family macropodidae. There are about 69 species of kangaroos in the world. They live in Australia, New Guinea and the nearby islands. Also everyone knows that kangaroo females have a special pouch where they carry their cubs. But not everyone knows that a kangaroo has a very short of pregnancy term. A baby is born about a month after conception. However, this is not a grown animal ready for life in the outside world. The size of a new-born kangaroo is only a couple of centimeters. And it weighs about a gram. In this embryonic state, the cub makes its way into the pouch, and a tiny kangaroo does not yet have hind legs, so he has to use the front ones. Moreover, the mother does not help him. She only licks the path to the pouch, for the cub immediately starts sucking on the nipple. Well, he doesn't actually suck it, because he is not yet able to. He is too small. Milk is secreted into his mouth with the help of a special muscle. Another particular thing about the kangaroo is that it has four nipples in his pouch. And each of them secretes a different kind of milk. So, kangaroos have four times of milk depending on the age of the cub. Sometimes a female has two cubs of different ages at once, and both are still in the pouch. In this case, two kinds of milks are secreted. In about 190 days, the cub becomes large and strong enough to climb out of the pouch. At first, he only sticks his head out. And this can continue for several weeks, until the cub feels safe enough to get out.