Marsupials are not mammals you hear about often, especially outside of Australia where the majority of them live. In fact, marsupials only make up about 5% of the total mammal population. There are anywhere between 250 and 330 species of marsupials in the world, but only one species lives in the United States. So what makes these mammals so unique? In this article, we will go over what makes a marsupial and introduce several types of marsupials.
What is a marsupial?
A marsupial is a type of mammal that gives birth to a newborn that is not yet fully developed. After birth, the mother carries it in a special external pouch until the baby has matured enough to live outside of her body. This is different than the vast majority of mammals, who are “placental”. Placental mammals, which includes humans, do not give birth to their young until they are fully developed.
The placenta is an organ that surrounds the baby in the womb, and provides nutrients, oxygen and disposes of waste. In placental mammals this organ is capable of sustaining the baby for the full term of its development. However in marsupials, the placenta is small and only able to sustain the baby for a short time.
After just a few days or weeks, the still-developing baby will crawl from the womb to the mothers pouch. At this point the young, often called a “Joey”, is tiny and hairless, with limbs that are not fully formed. The pouch will keep them warm and protected from the environment.
Pouches also contain one or more teats. The joey will suckle on the mothers teat and drink milk to provide it with nourishment to grow.
1. Opossums
Opossums can be found in North, Central and South America. In Central and South America there are over 100 different species of opossums! They are well known for their pointy snouts and scaly tails. Most opossums are adapted to do well both in trees and on the ground. They use their clawed hands, feet and long tail for grip and balance. Possums are opportunistic omnivores, which means they have a varied diet and will eat what they can find including insects, eggs, frogs, plants, fruits, rodents, birds or even sometimes scavenge dead animals.
Pictured here is the Virginia opossum, which is the only possum species found in North America. It is most active during the spring and summer. Females can give birth to 1-3 litters per year, and each litter averages 8-9 young.
That may seem like a lot of babies, but on average only one per litter will survive long enough to become a reproductive adult. After the young are old enough to leave her pouch, they will ride around on her back while she teaches them survival skills for their adult life. This is a vulnerable time for the mother and young, since carrying around that many babies tends to slow her down.
2. Sugar Gliders
You may be familiar with sugar gliders as they are common in the exotic pet trade, but did you know that these adorable mammals are marsupials? They can range in size from a mouse to a small cat, but one thing they all have in common is their patagium. A patagium is a membrane that helps an animal to glide or fly. In the case of gliders, an extra flap of skin extends from the front arm to the back leg.
The glider can leap off a tree and extend their limbs, expanding the extra skin and using it like a sail or parachute to catch air and glide longer distances than they would normally be able to jump. A useful trick to move from tree to tree, which is where gliders spend most of their life, or to escape a predator.
One of the best known gliders is the sugar glider. They are native to Australia, New Guinea and Indonesia, however have become popular worldwide as pets. Sugar gliders get their name from their love of sugary foods such as gum, sap, nectar and honeydew. They also eat insects and sometimes lizards or small birds.
One to two young are produced in each litter, and they can have multiple litters per year. The joey will remain in the pouch for at least 60 days after birth, which is reinforced with an extra “wall” so the baby will not be injured as the mother glides from tree to tree.
Sugar gliders are often confused with flying squirrels because they look so similar and are both gliders. However flying squirrels, which can be found all around the world including the U.S., are not marsupials and are not closely related to sugar gliders.
3. Tasmanian devils
The Tasmanian devil get’s its name from where it lives and its behavior. Historically, these animals were widespread throughout Australia and Tasmania, but now they are only found in Tasmania.
It is said the European settlers who first came across this animal added the moniker of “devil” after seeing how they viciously fight each other for food or to mate. They opening their jaws wide barring teeth and making all sorts of loud screaming and snarling noises. Add those to their characteristic red (on the inside) ears against black fur, and the name Tasmanian devil was born.
They are stocky and muscular, the size of a medium to small dog. They are currently the largest carnivorous marsupial, and relative to body size they have the most powerful bite of any living mammal carnivore! Their jaw can open up to 80 degrees to deliver a blow that can crush bone. They will often scavenge off carrion, but also will kill any smaller mammals like wallabies, wombats and rabbits.
Devils have a relatively short life-span, living only 2-5 years in the wild and averaging about 12 offspring that make it to adulthood. Females give birth to as many as 30 young at a time, but only have four teats for feeding in their pouch, so there is stiff competition.
The devil is an iconic symbol in Tasmania and is used as a mascot and in many logos on the island. It gained international fame when the Looney Tunes cartoon created the Tasmanian devil character.
4. Kangaroos
Kangaroos are native to New Guinea and Australia. There are four species of kangaroos and they are an iconic animal known around the world and them most common animal people associate with Australia. Perhaps this is because of their unique appearance and means of locomotion. Kangaroos are actually the only large animal that moves around by hopping.
On average they hop around 15 mph but can hop as fast as 45 mph over a short distance, thanks to their strong hind legs and long tail that helps them balance. Kangaroos are herbivores, eating mainly grasses and shrubs. They forage for food at dusk and dawn while spending hotter afternoon hours lounging in the shade.
Kangaroos are also the most common animal people associate with being a marsupial. This is probably because the joey’s make the pouch such a visible feature. When they are born, joey’s are only the size of a lima bean. They will grow in their mothers pouch for nine months before they can start to venture out.
Since kangaroos stand upright much of the time, the large lump of the joey developing in the pouch is quite visible. The joey will spend several weeks sticking its head out of the pouch before it feels safe enough to fully emerge. Even once the joey has left the pouch and is learning to get around on its own, it will continue to spend time going in and out of the pouch for another few weeks.
5. Wallabies
As you may have noticed from the photo, wallabies look a lot like kangaroos. They belong to the same family as kangaroos, and basically are only designated separately from kangaroos based on size. The term kangaroo is used for the four largest species from the kangaroo family, while the term wallaby is used for the eight smaller species of the kangaroo family.
Kangaroos in general live in open grass land, where wallabies smaller stature adapts them to live in more forested areas. Wallabies also have more compact legs than kangaroos, which gives them more mobility in forests and on rocky slopes. However, their smaller size makes them more vulnerable to predators like foxes, dingoes and feral dogs. They can use their strong back legs to deliver powerful kicks as defense.
6. Koalas
While you may have heard the term “koala bear”, koalas are actually marsupials, not bears. Koala’s are native to Australia, and live only in eucalyptus forests, feeding on the leaves of gum trees, which are too toxic for many animals to eat. They rarely come down from the trees, using their 2 opposable thumbs on each front paw to help them grip branches.
Koalas breed once per year or once every other year and give birth to a single joey (or sometimes twins). Because of the koalas strict diet of leaves, which are more difficult to digest and glean nutrition from, they have relatively low milk energy production rate. This means the joey must suckle for longer, and will may continue to do so for up to 12 months.
Before the joey can transition from a milk diet to eating leaves, the mother must pass on the gut bacteria that make it possible for koalas to digest all that eucalyptus. She will prepared a “fecal pap” made of predigested leaves and high levels of the gut bacteria that the joey will eat as a supplement. After 6-7 months, the joey will fully emerge from the pouch. It will ride on its mothers back for several months until it is fully weaned and ready to go off on its own.
7. Wombats
Wombats are short legged, ground dwelling mammals native to Australia. There are three species of wombat, and they live in a variety of habitats in southern and eastern Australia and Tasmania. Active mainly at dusk and overnight, they are not often seen. Wombats are burrowers, and will dig extensive burrow systems with their front teeth and sharp claws. They are herbivores that eat mostly grass and sedge, but also herbs, bark and roots. Their rodent-like incisor teeth allow them to gnaw through tough vegetation.
Wombats have a backward-facing pouch, so the pouch opening does not face towards their head, where dirt could get in during their burrowing. Females give birth to a single baby after about 30 days, and the developing wombat will stay in the pouch for about 6-7 months.
8. Bandicoots
There are more than 20 species of bandicoots, a small to mid-sized marsupial. They have a long pointed snout, large ears, round black eyes and a long hairless tail. Size of the bandicoot varies widely across the different species with the largest being about the size of a house cat. They are nocturnal and use a sharp sense of smell, acute hearing, and sharp claws to dig holes and find food. Bandicoots diet consist of spiders, insects, small reptiles, roots, berries, seeds and tubers.
Bandicoots are one of the few marsupials that have a developed placenta, however it is still small and lacks certain features that would make it a true placenta in the category of the placental mammals. Like wombats, their pouch is rear-facing which can aid in preventing dirt from entering the pouch when digging.
9. Bilbies
Bilbies are sometimes called “rabbit-bandicoots” due to their appearance of having a bandicoot body with a rabbit’s ears. They are desert dwellers and those large ears help them to radiate off excess body heat, as well as give them excellent hearing. They are nocturnal omnivores like bandicoots, however they are much better diggers and actually create underground burrows and tunnel systems.
Within their home range they will have up to a dozen burrows. They use these to hide from predators and get out of the desert heat. Another adaptation they have for life in a dry climate is they get all of the moisture they need from the food they eat. This way they don’t have to find other sources of water.
Like other digging marsupials, the pouch of the bilby faces backwards to avoid contamination by dirt. Due to habitat loss and competition with other animals, the bilby is becoming endangered. Australia has a recovery plan that involves captive breeding and reintroduction to previous native territories.
10. Quolls
There are six species of Quolls, four found in Australia and two in New Guinea. They are about 10 – 30 inches long, with 8 – 14 inch long furry tails. They have a long pointed snout with a pink nose, and their coat has white spots. Quolls are mostly solitary animals that sleep in log or rock dens during the day and hunt at night. They are carnivorous, and eat mainly lizards, frogs, birds, insects and reptiles.
Larger species of Quoll will eat possums, rabbits and hares. They can get their full requirement of water from the meat they eat. A useful trick that helps them survive during times of drought. Quoll numbers are in decline due to two introduced species, cane toads and foxes. Cane toads are poisonous and can often kill a quoll if they eat one. Foxes not only prey on quolls, but also compete with them for food such as rabbits.
The female will give birth to up to 18 babies. However, only six will ultimately survive to exit the pouch because she only has six teats for feeding. They will emerge from the pouch after nine weeks, and will spend about six weeks riding on their mothers back.
11. Numbats
Numbats used to be fairly widespread across southern Australia, but habitat loss and the introduction of feral cats has dwindled their numbers. Currently they are an endangered species and are only found in small colonies in the western part of the country. Numbats are small, only about 14-18 inches long, with a pointed snout, striped face, furry tail, and 4-11 white stripes across their hindquarters.
They are very specialized marsupials in that their diet consists almost entirely of termites. In fact, they need to eat 20,000 termites per day! While most small terrestrial marsupials are at least somewhat nocturnal, numbats must be active during the day to find active termite nests. Similar to other termite eaters, they have a long, thin tongue coated with sticky saliva. They also have ridges on the soft palate inside their mouth. This helps them scrape termites off their tongue to be swallowed.
Unlike most marsupials, numbat females do not have pouches. They still give birth to underdeveloped young that then have to suckle on milk from their teats for several weeks before they are fully grown, they just do not do this inside of a pouch. The teats are located in an area of bushier, courser hair, and the surrounding area of tissue swells a bit while the female is lactating, providing some protection.
12. Brushtail possums
This possum, named for its bushy tail, is native to Australia but is also and invasive species in New Zealand. It is the second largest possum species, and is adaptable to a variety of environments. So adaptable in fact, it can live close to humans in urban and suburban environments where it sometimes can be found foraging in fruit trees, backyard gardens or even food scraps in trash. Brushtails have a preference for eucalyptus leaves, but also eat other flowers, fruits and seeds, insects, birds eggs and small vertebrates.
Females can breed any time of year, and have only a single baby at a time. After a 16-18 day gestation, the baby moves to the pouch for another 4-5 months. Once out of the pouch, the young will stay in the den or ride on mom’s back for another few months.
13. Water opossum
As the name would suggest, the water opossum is a species of marsupial that is associated with water. They are considered to be the most aquatic out of the marsupials and are found near and in freshwater streams in parts of Central and South America.
Their aquatic lifestyle has evolved with some unique adaptations that allow them to thrive in the water. They have incredibly dense, short fur that essentially repels water. Perhaps the most impressive adaptation though, is their specialized pouch that protects their young while they swim. The opening of their pouch is equipped with strong muscles that essentially creates a seal to protect their babies while they swim. And unlike all other species of marsupials, both the male and female have a pouch.
14. Shrew opossum
The shrew opossum is an adorable marsupial that is found only in the Andes Mountains in South America. They get their name from their small size and shrew-like appearance. Not much is known about these mammals which is likely due to the fact that they inhabit tough terrain, making it difficult to located and research them.
They are almost entirely carnivorous, feeding mostly on insects and small vertebrates. They are believed to spend much of their time in burrows and have poor eyesight, relying on their other senses to navigate. Shrew opossums don’t actually have a pouch to carry their young, instead they are thought to carry them but will also leave them behind in their burrows from time to time.
Melanie has a degree in Environmental Science and has always been interested in all things nature from wildlife to plants. In her spare time she enjoys hiking, travel, reading, photography and crochet.