Marsupials

    A  pouch is one of the features that differentiate marsupials from other animals although not all have a permanent pouch and few have none at all. They are similar to mammals in being covered in fur and bearing live young which are suckled by the mother. In marsupials the gestation period is very short,which results in the birth of undeveloped young joeys. Although blind, without any fur on their bodies, and with hindlimbs only partially formed these tiny newborn marsupials have well developed forelimbs with claws that enable them to make their way into the pouch and latch on to a teat and continue their development in the pouch.
    The short gestation period is compensated by the lengthy period of lactation, during which the young joey remains in the pouch and the composition of the milk produced by the mother changes, depending on the developmental stage of the young.    (Source: Australian Wildlife)