Tag Archives: platypus

Drought and human expansion are driving the platypus extinct

Woes seem to keep piling onto poor Australia: new research shows that the continent’s iconic and unique platypus is at risk of extinction.

Image credits hobvias sudoneighm / Flickr.

The intense and prolonged drought plaguing the land down under is placing enormous strain on the platypus, a new study reports. The rivers and waterways that make up this species’ natural habitat are drying up, leaving the animals stranded, the researchers explain.

Going through a lot

Although not much is known about their natural distribution or abundance (the species is nocturnal and quite shy), platypuses were once considered widespread throughout eastern Australia and Tasmania. However, new research led by members from the University of New South Wales (UNSW) in collaboration with the Taronga Conservation Society showcases that the species is in dire need of help. It is experiencing heavy pressure from both natural and man-made factors including severe drought, water resource development, land clearing, and changing climate. The team warns that action is urgently needed to save the platypus from potential extinction.

Lead author Dr Gilad Bino, a researcher at the UNSW Centre for Ecosystem Science, said action must be taken now to prevent the platypus from disappearing from our waterways.

“There is an urgent need for a national risk assessment for the platypus to assess its conservation status, evaluate risks and impacts, and prioritise management in order to minimise any risk of extinction,” says Dr. Bino.

“These dangers further expose the platypus to even worse local extinctions with no capacity to repopulate areas.”

The species is most impacted by current climate conditions and habitat destruction through land clearing and fragmentation from dams and weirs, the team reports. They further explain that platypus numbers have almost halved since European colonists first settled Australia, with local populations going extinct across 40% of the species’ range. Considering the current drought and the likely increase in drought frequency and duration in the future (due to climate change), things are only going to get worse for the platypus.

While the International Union for Conservation of Nature (IUCN) recently downgraded the platypus’ conservation status to “Near Threatened”, it remains entirely unlisted under most local jurisdictions except in South Australia, where it is considered endangered.

Apart from climate change and its associated extremes in weather and precipitation patterns, the chief threat to platypus’ long-term viability is humans, the team explains. The animals live or have traditionally lived in areas that are still experiencing extensive human development.

“These include dams that stop their movements, agriculture which can destroy their burrows, fishing gear and yabby traps which can drown them and invasive foxes which can kill them,” says study co-author Professor Richard Kingsford, also from the UNSW Sydney Centre for Ecosystem Science.

Luckily for the strange mammal, it’s not yet extinct. If preventative measures are taken now, says Professor Brendan Wintle, a study co-author from The University of Melbourne, we can turn their fortunes around. He explains that mitigating or stopping new threats (such as new dams) from impacting the species’ range can help “even a presumed ‘safe’ species such as the platypus”.

Still, the paper highlights the “urgent need” for national conservation efforts focusing on the platypus. However, they add that many other native Australian species are also threatened with extinction.

“[Preventive measures are] likely to be more effective than waiting for the risk of extinction to increase and possible failure,” Prof Wintle said. “We should learn from the peril facing the koala to understand what happens when we ignore the warning signs.”

Such measures include “increasing monitoring, tracking trends, mitigating threats, and protecting and improving management of freshwater habitats.”

Meanwhile, the team plans to continue researching the ecology and possible conservation practices for the platypus to help guide effective policy and management programs in the future.

The paper “A stitch in time – Synergistic impacts to platypus metapopulation extinction risk” has been published in the journal Biological Conservation.

Artist impression of Eretmorhipis carrolldongi. Credit: Gianluca Danini.

Ancient Triassic reptile looked like a platypus

The platypus is one of the most awkward creatures in the animal kingdom. Part duck, part reptile, part mammal, the platypus is famous for being one of the few mammals in the world that lays eggs. Remarkably, some of its features are shared by an ancient platypus-like reptile called Eretmorhipis carrolldongi, which lived around 250 million years ago — not too long after a devastating mass extinction.

Artist impression of Eretmorhipis carrolldongi. Credit: Gianluca Danini.

Artist impression of Eretmorhipis carrolldongi. Credit: Gianluca Danini.

Researchers had known about E. carrolldongi for decades but the excavated specimens lacked skulls. it was only recently that Chinese paleontologists at the Wuhan Centre of China Geological Survey found specimens with complete skulls in Hubei province — and it looks like the skull was quite an important puzzle piece.

“This is a very strange animal,” Ryosuke Motani, a paleontologist at the University of California and co-author of the new study, said in a statement. “When I started thinking about the biology I was really puzzled.”

Judging by the shape of its skull, Eretmorhipis must have accommodated a bill of cartilage. And just like the modern platypus, the Triassic creature had large holes in the bones of the middle of the bill, suggesting a shared function. In the platypus, the bill is equipped with receptors that allow it to hunt prey by touching it in muddy streams. Because visibility is low, the platypus also has very small eyes.

Eretmorhipis, which also had small eyes, likely evolved this feature because it shared a similar environment to the platypus. The ancient reptile lived in an area covered by a shallow sea only a meter deep, which rested on a carbonate platform. Researchers presume its diet consisted of shrimp, worms, and other invertebrates.

Complete fossil and line drawing of Eretmorhipis carrolldongi. L. Cheng et al, Scientific Reports.

Complete fossil and line drawing of Eretmorhipis carrolldongi. L. Cheng et al, Scientific Reports.

Other defining features include four flippers for swimming and steering and bony plates which ran down the animal’s back. Eretmorhipis was likely a poor swimmer though, judging from its long and rigid body.

“It wouldn’t survive in the modern world, but it didn’t have any rivals at the time,” Motani said.

Eretmorhipis wasn’t related in any way to the platypus’ monotreme lineage but rather with the dolphin-like ichthyosaurs.

The findings appeared in the journal Scientific Reports. 

A platypus casually having a swim in a stream. Credit: Wikimedia Commons.

Why are there mammals that lay eggs?

A platypus casually having a swim in a stream. Credit: Wikimedia Commons.

A platypus casually having a swim in a stream. Credit: Wikimedia Commons.

You probably know that you’re a mammal. Dogs, cats? Those are mammals, too. What about dolphins and whales? Yup, those are too — they’re called marine mammals. What all of these species have in common is that the female feeds her young on milk from her own body and gives birth to live babies. But its only the former that’s a definite and unique mammalian trait: oddly enough, there are mammals that lay eggs. They’re called monotremes, and it’s a group that is only comprised of two members that are still alive today: the platypus and echidna.

What gives?

I’d argue that the main reason why mammals have become so successful is due to their phenomenal evolutionary jump from laying eggs (oviparous) to birthing live young (viviparous). Of course, some environments are better suited for animals that lay eggs, but mammals have the huge advantage of producing young that are more developed.

An egg is a sealed system, so the development and size of an infant are determined by the amount of nutrients within the egg. The largest egg, which belongs to the ostrich, can only produce an infant that’s about 25 cm (10 inches) in size and weighs about a kilogram. In contrast, mammals can grow an infant for much longer than an egg and produce much more developed young that are better equipped to survive. For instance, an elephant will gestate for more than 600 days, giving birth to a 160-kilogram infant. What’s more, during pregnancy, the infant is protected against the environment and predators, unlike an egg which can be easily predated and broken.

This begs the question: why aren’t the platypus and echidna also live-bearers? Jurassic mammals diverged into a lineage leading to the monotremes and a lineage leading to the therians (marsupials and placental mammals) about 166 million years ago. Marsupials and placental mammals diverged from each other later — about 145 million years ago. Because monotremes are older than marsupials and placental mammals, many presume that the platypus (Ornithorhynchus anatinus) is a primitive animal.

Its wacky appearance —  part bird, part reptile, part mammal — seems to suggest something ancestral too. Its legs also come out on the sides like a reptile rather than from underneath. The female lays one to three eggs in a burrow and then curls around them to provide warmth. Ten days later, the lima bean-sized younglings hatch. The mothers nurse their young with milk — but not from nipples (which they lack) but rather from the pores in their skin. The milk collects in grooves on the female’s stomach, which the babies lap rather than suck. Four long months later, the babies are ready to come out of their burrows and swim just like their mums

The strangeness doesn’t stop there. Male platypuses have venomous spurs on their back legs. Its venom is strong enough to kill a dog, but not potent enough to kill humans — although the pain is extreme and can last for days — even months. Many reptiles have venom and since reptiles are often considered primitive, this is another cue that the platypus is an inferior creature, and thereby explaining the mammal’s rather weird egg-laying. But that’s not really true.

“Platypuses do not have “reptilian” traits, they have ancestral amniote traits [enveloping developing embryos in protective layers]. The most obvious one is egg-laying. Platypuses retain a variety of amniote genes related to egg development that have been lost in the therians. In addition to retaining some ancestral amniote traits, platypuses have acquired new traits. One such trait is venom production [..], platypus venom is not “reptilian” but an independently acquired trait and merely convergent upon reptile venom. Additionally, platypuses have an electrosensory system that allows them to detect prey based on electrical fields. Possessing these traits, a platypus might look at us and ask, “Who are you calling ‘primitive’?” since we preserve the ancestral (“primitive”) state by lacking both features,” according to the Nimravid blog.

Like with most other creatures, today’s monotremes are not primitive but rather adapted to their particular environments. What’s more, evidence suggests that the very first mammals were egg-layers and may have possessed a cloaca. In fact, monotreme means “single hole” — referring to the multi-purpose opening in their rear end used for both excretion and reproduction (the cloaca).

Plaster cast of a platypus egg. Photograph: Elsa Panciroli/National Museums Scotland

The odd monotremes dominated Australia for millions of years until their pouch-bearing cousins, the marsupials, invaded the land down under 71 million to 54 million years ago. Examples of extinct monotremes include Zaglossus hacketti (a long-beaked echidna from Western Australia that is dated to the Pleistocene) and Obdurodon tharalkooschild (a giant, carnivorous platypus with fearsome teeth, twice the size of today’s platypus). When there wasn’t any competition, the monotremes did just fine laying eggs, but when marsupials invaded they stood no chance.

According to evolutionary biologist Matthew Phillips of the Australian National University in Canberra, the reason why egg-laying mammals still exist today is that the surviving ancestors sought refuge where marsupials could not follow — the water. This theory bodes well with platypuses, which are aquatic. However, echidnas solely dwell on land. A study performed by Phillips and colleagues performed a genetic analysis finding that echidnas diverged from platypuses only 19 million to 48 million years ago. This means that the echidnas shared a semiaquatic ancestor and only later colonized the land. Hints that this might be true include the echidna’s streamlined body, hind limbs that look like they once served as rudders, and a ducklike bill during embryonic development.

It worth mentioning that different animals have adopted different strategies that are shared mainly by a group. For instance, 15 to 20 percent of the 9,000 known species of snakes and lizards are live-bearers. So are some species of fish, such as guppies and sharks.

If anything, monotremes are a testament to the immense diversity of animal life. What’s more, studies of the platypus’s genome — such as those performed by Stanford University’s Craig Lowe — might one day shed light on the evolution of pregnancy.

‘Platypus-zilla’ fossil unearthed in Australia

A giant platypus fossil, measuring more than 1m long (3ft) was discovered in Queensland, Australia. The animal lived 5-15 million years ago, as paleontologists explain in the journal Vertebrate Paleontology. Until now, the oldest fossil was dated 100.000 years ago.

platypuszilla

As if the evolutionary status of the platypus wasn’t extraordinarily complicated as it is, this finding adds even more complexity to the issue. The platypus is a frequent subject of research in evolutionary biology. In 2004, researchers at the Australian National University discovered the platypus has ten sex chromosomes, compared with two (XY) in most other mammals (for instance, a male platypus is always XYXYXYXYXY). Prof Mike Archer, from the University of New South Wales believes this fossil highlights an entire branch of their family tree that we previously knew nothing about.

“Suddenly up pops ‘playtpus-zilla’ – this gigantic monstrosity that you would have been afraid to swim with. “It indicates there are branches in the platypus family tree that we hadn’t suspected before.”

platypustoothInterestingly enough, all that remains today from the fossil platypus is a single tooth – yep, paleontology is just this advanced and this good – all this information can be derived from a single, fossilized tooth. Not only did paleontologists figure out that they were dealing with a new species of platypus, two times bigger than the one that lives today, but they also figured out that it usually fed on crustaceans, turtles, frogs and fish. However, it’s still impossible to know exactly how it looked like.

“I guess it probably would have looked like a platypus on steroids,” said Prof Archer.

Platypus fossils come in very short supply, and researchers are forced to work with limited information, relying on assumptions more than facts. But this fossil shows us a bit of the larger picture.

“We have been naively led to suspect that maybe it was just one lineage of strange animals bumbling its way through time and space at least for the last 60 million years. The discovery of this new one was a bit of a shock to us. It was a wake-up call that the platypus’s story, the more we know about it, is increasingly more complicated than we thought.”

Hopefully, as more fossils are discovered in Australia, we will be able to find out more about these unique, enigmatic animals.