Marsupials are underrated Australian survivors. It's time to get to know them better

Australia Broadcast Center

3 days ago

A small golden animal with shovel-like claws swims through the red sand of Australia's central desert in pursuit of its supper.
Over millions of years, it's lost its eyes, but it is still a fierce hunter.
Even though it has no external ears, it can sense the smallest of movements.
The Anangu people call it "itjaritjari".
When Western scientists first stumbled across the cryptic animal in the 19th century, they dubbed it the "marsupial mole" because it bore a striking resemblance to the "true moles" they knew.
Some even debated whether it was a missing link between mammals and marsupials. Then they discovered it had a pouch.
At the time Notorctes typhlops was described, scientists such as John Gould regarded marsupials as primitive animals.
Just a few years earlier, in 1863, he wrote:
"This is a very low form of animal life, indeed the lowest among the Mammalia."
The subject of his disdain? The majestic kangaroo — and, by extension, all Australasian marsupials.
Marsupials had been respected and understood by Indigenous Australians for tens of thousands of years when Gould penned those words.
Today, many marsupials have become Aussie icons — think kangaroos, koalas and wombats — and have arguably gained more attention than other Australian mammals such as rodents and bats.
Yet our knowledge of this amazing group as a whole — even the popular animals — is still "inadequate", Tim Flannery argues.
Professor Flannery is famous for his work as a climate advocate and director of the Australian Museum, but marsupials have been his passion since the 1980s.
"If you want to know what it really means to be Australian, it pays to give the marsupials a little bit of time," he says.
Today, two-thirds of the world's 300-plus marsupial species are found in Australia.
Their story on this continent starts at least 55 million years ago.
The earliest marsupials were probably like today's bandicoots, small omnivorous creatures that can breed at a rate of knots when conditions are correct, Professor Flannery suggests.
Fossils from the Murgon fossil site in Queensland back him up, revealing ancient bandicoots and tiny climbing creatures that might have looked like today's phascogales.
Their ancestors travelled here across the supercontinent of Gondwana, from what is currently South America through ancient Antarctica until they reached a land bridge that is now Tasmania.
"Australia was still very much a polar environment. Everywhere south of northern New South Wales was all within the Antarctic circle," Professor Flannery explains.
These early marsupials shared their damp polar world with the world's first songbirds and the egg-laying monotremes, which would evolve into today's platypus and echidna.
The "scarce" fossil record also shows bats as well as hints that a few non-marsupial mammals were present on the continent at the same time.
But marsupials may have had an evolutionary advantage over mammals.
Marsupials have it easy in the birthing department compared to placental mammals like us.
They have a super pared-back placenta — so don't nourish their young in their uterus for long. They birth underdeveloped joeys (sometimes the size of a grain of rice) and grow them up externally, usually in a pouch.
When colonial scientists like Gould encountered marsupial reproduction, it was cast as an "intermediate" step between egg-laying monotremes and "high" placental mammals.
In other words, it was thought that mammals evolved from marsupial-like creatures.
And only monotremes — platypus and echidna — were considered lowlier.
This idea was flipped upside-down like a ring-tailed possum on a wire by Heather White in 2023.
Dr White, who is a researcher at London's Natural History Museum, studied ancient skulls, and showed that marsupials evolved from early placental mammals.
This means marsupials are hyper-specialised placental mammals after all. Sorry Gould.
And their pouch may have been the secret to their evolutionary success, Professor Flannery suggests.
Dunnart females are ready to breed at three months old, and have 14-day pregnancies of up to 10 young at once — often from multiple fathers.
When times are hard, they can hit "pause" on their pregnancies.
This "eruptive and rapid" breeding may have given marsupials the edge they needed to cross the ancient polar land bridge from South America to Australia when placental mammals did not.
And sure, there are no marsupials that have flippers like whales or that can fly like bats.
But we should celebrate them for what they can do, says kangaroo fan Vera Weisbecker, who runs the bones and biodiversity lab at Flinders University.
"Kangaroos are the biggest animal to ever hop, ever. This is biomechanically next to impossible at such large sizes," Dr Weisbeker says.
As the continent changed over time, many species adapted to new challenges and habitats.
The ancestors of today's itjaritjari, and its northern cousin the kakarratul (Notoryctes caurinus) as it is known by Ngaanyatjarra communities, appear in the fossil record about 20 million years ago.
These early marsupial moles transformed adaptations used for foraging in soft rainforest to survive in the desert as the continent dried out.
They weren't the only animals to adapt to arid conditions.
Tiny carnivorous desert-dwelling mulgara (Dasycercus sp) produce super-concentrated urine and seemingly get all their moisture from their prey's flesh.
The mainly herbivorous mala (Lagorchestes hirsutus) takes this feat one step further. It can survive in the desert without water or juicy insects, getting all its moisture from plants.
Australia's climate is tough, but Professor Flannery says the real challenge of this continent is the soils.
"The surface layer of the rocks has been leached of all of its nutrients a long time ago, with a few exceptions," he says.
As a result, Professor Flannery believes the capacity of marsupials to survive on "miserable and meagre food" is underrated.
"The good old euro can eat spinifex and survive which is bloody miraculous from a metabolic point of view," he says.
Not all marsupials live in the arid zone.
The cuscus (Spilocuscus maulatus), which is Professor Flannery's favourite underrated marsupial, along with the striped possum (Dactylopsila trivirgata) and tree kangaroos can still be found in pockets of dense rainforests in northern Australia.
Yet despite their tenacity over the past 55 million years, many marsupials are now threatened with extinction.
There are now around 159 marsupial species in Australia — and an estimated 40 per cent of them are threatened.
Since colonisation, 17 Australian marsupial species have disappeared.
This is an extinction rate of nearly 10 per cent — well above the global mammal extinction rate of 1.4 per cent over the same period.
Marsupial moles — the itjaritjari and kakarratul — are rarely seen. Little is known about their range and distribution.
The karkarratul is considered stable, but the itjaritjari is listed as endangered.
Both species face predation by introduced species such as foxes and cats, and changes to their habitat.
Despite being evolutionary wonders, the idea that marsupials are "inferior" to placental mammals still remains today, Professor Flannery says.
Helping turn that notion on its head is Greg Irons, manager of the Bonorong Wildlife Sanctuary in Tasmania.
As a wildlife rescuer, he hears concern about the charismatic cuties such as Tasmanian devils in his home state or bilbies, koalas and numbats on the mainland.
But Mr Irons worries that less famous marsupials blur into "just another hopping thing", when they each have a unique (and underrated) role in the ecosystem.
On mainland Australia, little diggers like bandicoots and bilbies and boodies eat seeds, travel and then disperse those seeds when they come out their back end.
They pockmark arid environments with holes, increasing water penetration after rain and improving conditions for the young plants they help transport.
In Tasmania, bettongs use their pointed snout to root out fungus from the forest floor, scattering spores and spreading fungi that keep forests healthy.
"We've got kids at school that can all tell you what a lion, a tiger, and probably 40 different species of dinosaur are, but they cannot tell you what a bettong is," Mr Irons says.
"Yet this animal could be responsible for the entire communication and health of the forest that allow us to breathe."
Thanks also to Dr Jack Ashby, assistant director of the University Museum of Zoology, Cambridge for his input.