When we talked about our dear koala, we mentioned that it is a marsupial mammal.
Let’s take a step back and understand what “marsupial” means.
Mammals are divided into three major groups based on their mode of reproduction.
Most species belong to the infraclass Eutheria or Placentalia, which includes humans. Females give birth to well-developed offspring, after growth within the placenta.
The most primitive group is the Prototheria (also known as Monotremes), the only mammals that lay eggs. They are considered mammals because they nurse their young like all others. This subclass includes only the platypus and the echidna, but we will talk more about them later as they are representative animals of Australia.
Finally, there are the Metatheria or Marsupials, which give birth to underdeveloped, blind, and hairless joeys, then transfer and nurse them in the abdominal pouch, until fully developed.
Thanks to recent studies, scientists estimate that this particular characteristic originated between 70 and 90 million years ago in the late Cretaceous. They also found that marsupials are not more primitive than placentals but evolved simultaneously and then distributed differently around the world.
Currently, there are about 70 species in North and South America and other 200 species in Australia and Southeast Asia, adapted to various environments and food sources.
Now let’s look at some of the main families of Marsupials.
Didelphidae are generically called opossums. Small (under 50 cm), arboreal and omnivorous animals, that live in the Americas from the United States to Argentina. The most famous species are the common opossum (Didelphis marsupialis) and the Virginia opossum (Didelphis virginiana).
Among the lesser-known but noteworthy members of this family are the yapok (Chironectes minimus), also known as the water opossum because it is the only marsupial to live in an aquatic habitat in Central and South America, and the yaca (Thylamys elegans), endemic to Chile, which can store fat in its tail as an energy reserve during periods of food shortage.
You have probably heard of the Tasmanian devil (Sarcophilus harrisii), thanks to the famous character Taz from Looney Tunes. Yes, it is a carnivorous marsupial, belonging to the family Dasyuridae.
Myrmecobiidae, commonly called numbats, have specialized in a diet made almost exclusively of termites and ants.
There are also two species of marsupial moles (Notoryctidae), which live in the Australian deserts. They are insectivorous and almost completely blind like European species.
Besides our friend the koala, which we have already talked about in the previous post (click here to read it), there is another iconic Australian animal, which gives its name to the family Vombatidae: the wombat. An animal with so interesting features that I will write a whole post about it.
The gliders (Petauridae) are small, arboreal marsupials, characterized by a membrane that connects their front and hind legs, allowing them to move from tree to tree, gliding. They are often confused with flying squirrels, but they have no real connection, except for some physical similarities.
Finally, the most famous marsupials, which we all immediately think of when asked “who are the Marsupials?”: the Macropodidae, family of kangaroos, wallabies and quokkas.
They are all terrestrial and their hind legs are muscular and significantly longer than the front ones, adapted for jumping. Their strong tail helps them both for balance in jumping and support, like it was an additional leg. The only exception is the tree kangaroo (genus Dendrolagus), specialized for life in trees.
All species are predominantly herbivorous or frugivorous, meaning they feed on fruit.
The red kangaroo (Osphranter rufus) is the largest living marsupial, as well as the largest terrestrial mammal in all of Australia.
Adult males can exceed 180 cm in height, and the largest ever recorded specimen was 2.10 m tall and weighed 90 kg.
Did you know all of them? Is there any that particularly intrigues you and you would like to learn more about? Let me know in the comments below!
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