How do koalas and other marsupials carry and feed their babies?

Marsupials, including koalas, kangaroos and wallabies, give birth to extremely underdeveloped young after relatively short pregnancies. The tiny newborn then crawls to a nipple, often inside a pouch, where it stays protected and nourished. The pouch is a hallmark of many marsupials, though not all species have a true pouch structure. This reproductive strategy shifts much of development to a safe external environment after birth.