Australian Mammals

Mammals are vertebrates that give milk to their young. Most are hairy.

There are three great groups of mammals on Earth, subdivided according to how their young are born: (1) monotremes which lay eggs (many mammals used to lay eggs in the Cretaceous, but today there are only four species left, and found only in Australia and New Guinea); (2) marsupials, whose young are born in a very embryonic state and continue development attached firmly to the mother’s teat in a pouch or pouch-like flap of skin; and (3) placentals, whose young are born at a much more advanced stage.

Monotremes – egg-laying mammals

The platypus, arguably the world’s strangest mammal, in found only in Australia. The first specimens taken to England were regarded as a hoax – no animal could look like that! And that was even before it was known that although they’re hairy and give milk to their babies they lay eggs, that they are the world’s only known poisonous mammal (the male has a venomous spur on his hind leg) and they find their prey not with eyes and ears but by electricity (the rubbery duck-like bill is sensitive electric impulses emitted by their prey’s muscles and transmitted through the water).

There is one species of echidna in Australia, and 2 in New Guinea. Like the platypus, they lay eggs, but unlike the platypus the female, prior to laying, forms a small pouch in which to carry the eggs and young. Echidnas are spiny, but have very different spines and faces to hedgehogs and porcupines, both of which are placentals and not at all closely related. The echidna’s closest living relative is, of course, the platypus.

Marsupials – pouched mammals

Major divisions of marsupials:

a. mostly herbivorous, with two front teeth, and the 2nd and 3rd toes of the hind feet joined as a grooming tool, front feet often true hands with opposable thumbs

They include the kangaroos, wallabies, rat-kangaroos, koalas, wombats, possums (NOT the American opossums – see below), gliders, cuscuses and honey possums (which although called possums are in a group of their own)

b. mostly omnivorous (eating a variety of plant and animal matter), with many front teeth, and the hind foot resembling herbivorous marsupials in having the 2nd and 3rd toe joined (used for grooming)

These include the bandicoots and bilbies.

c. mostly carnivorous (or insectivorous), and mostly with many front teeth, and without the 2nd and 3rd toe joined

These include the ‘dasyrurids’: the well-known Tasmanian devil, the quolls (largest mainland predatory marsupials: cat-sized), phascogales, kowari, dunnart, antechinus, dunnart, planigale. The opossums of the Americas resemble this group more than they do the Australian possums and other herbivorouys marsupials, but are not as closely related as once thought.

Also in the general carnivorous/insectivorous group are the numbat and the marsupial ‘mole,’ both sufficiently different from other marsupials to have whole taxonomic orders to themselves.

Placentals (young born at a more advanced stage)

Australia has NO native placental carnivores (i.e. cats, dogs, bears, raccoons etc – but the dingo, now known as Australia’s wild dog, was introduced about 3000 years ago), NO hoofed animals (deer, goats etc.) NO primates (monkeys and apes) and indeed NO native placentals except those listed below.

Bats -

• megabats (do not echo-locate but use sight, sound and smell in much the same way as most other mammals, usually eat fruit or nectar or both, and found from Africa to the Southwest Pacific). There is no evidence of the megabats being here more than about a million years.
• microbats (echo-locate, usually eat insects, found on all continents). The microbats reached Australia many million of years ago.

Rodents – in Australia all native rodents are in the rats-and-mice family (no native squirrels, porcupines, beavers etc.). Their ancestors appear to have arrived here around 4 million years ago and have diversified since then into many different species, especially in drier regions (although several species are very common in our rainforests). In fact about a quarter of all our mammal species are rodents.

Marine mammals – these include seals, sea-lions, dugong, dolphins and whales

Click here for a more detailed overview of our  Australian mammals