The most well-known defining feature of marsupial mammals are the females' pouches. They give birth to live offspring, but with significantly shorter gestation periods than placental mammals. Offspring are born as not much more than embryos. They continue developing in the pouch, taking nourishment from the mother's milk. In prehistoric times, marsupial mammals were more common -- during some periods even more common than placental mammals -- but today there are relatively few of these types of animals.
Kangaroos are probably the most famous marsupial mammals. There are more than 50 different kangaroo species, including red kangaroos, gray kangaroos and some smaller cousins of the same family, like wallabies, wallaroos and quokkas. Red kangaroos are the biggest marsupial mammals in the world today. Kangaroos are indigenous to Australia and/or New Zealand and other nearby islands. Their offspring are called "joeys." These marsupials are almost as well-known for their large feet and tails and giant hops as they are for their pouches. They are grazing herbivores, meaning grasses and foliage are their main source of sustenance.
Opossums are the only marsupial mammals indigenous to North America. Mothers carry their young in the pouch until they're 2 to 3 months old, then they continue carrying offspring around on their backs for about another month or two whenever they venture out of their den. These nocturnal marsupials are roughly the size of domestic cats, but they're much slower and less graceful than felines. Opossums are omnivorous, eating pretty much anything they can find; among other things, they eat fruits, vegetables, grasses, leaves, carrion, eggs, snails, insects and even small rodents and snakes.
Though they're often called koala bears, these marsupial mammals aren't bears at all. Mothers carry their offspring in pouches for around six months; afterwards, babies hang out on their mothers' backs most of the time until they're about 1 year old. These animals are native to eastern Australia, where they spend most of their time in the eucalyptus trees, feasting on their leaves and sleeping for up to 18 hours every day. The diminishing woodlands in Australia is a great threat to these marsupials, who require a territory of about 100 trees per animal to survive.
Other Marsupial Mammals
Kangaroos, opossums and koalas are arguably the most famous of the marsupial mammals. Though there are relatively few marsupial mammals in the world as compared to placental mammals, there are a number of others, and they're a diverse bunch. The 17 species of bandicoots are small relatives of kangaroos that live in Australia, New Zealand and other area islands. They're the fastest known reproducing mammals, giving birth 12.5 days after mating. Wombats live in Australia and on surrounding islands, carrying their offspring in their pouches for about five months. Tasmanian devils, dasyures and phalangers are other examples of marsupial mammals.
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Eric Mohrman has been a freelance writer since 2007, focusing on travel, food and lifestyle stories. His creative writing is also widely published. He lives in Orlando, Florida.