Marsupials usually undergo premature births (about 4-5weeks), exposing the infants to great environmental risks. Due to early birth, there is insufficient time for a complex placenta to be formed to protect the embryo from its mother's immune system.
When the infants are borned, their front limbs are much more developed then the rest of their body. Hence, the limbs are vital in helping them to climb to their mother's nipples which are located inside the marsupium. Every adult marsupial has 6-7 nipples, each catering to one newborn. The offsprings feed on milk that lactates fr
om their mother's nipples, providing them with the necessary nutrients to grow.
Kangaroo newborn sucking on its mother's nipples in the pouch.
