Echidna evolution on an ever-changing Earth

One of Australia’s most unique and fascinating species is undoubtedly the spine-covered, egg-laying mammal we now know as the short-beaked echidna. It may have ancestors that survived both the dinosaurs and a 2-million-year ice age but with their world changing in new ways, could human beings be what brings this incredible animal to the brink? 

The monotreme mystery 

The echidna is one of Australia’s most widespread mammals, yet scientifically it remains mysterious. One of the most unique aspects is that the echidna challenges the very definition of a mammal. Whilst it has fur and produces milk for its young like other mammals, the echidna lays eggs like a reptile. This unique mammal helps create a living subset of our most primitive mammalian ancestors, known as the monotremes.  

Australia is lucky to be home to the two known families of monotreme - the platypus and the echidna. Although they look nothing alike today, new research suggests echidnas evolved from semi-aquatic ancestors similar to the platypus. Their transition from water to land is considered extremely rare in evolutionary history, making them even more unique. 

Remarkable resilience

Echidnas have remarkable characteristics that have helped them evade predation and survive the harsh changes in our landscape over thousands of years. Their ancient lineage means their early ancestors roamed the earth with dinosaurs, with an even closer relative surviving the most recent ice age that lasted over 2 million years. So, what is the echidna’s secret to success? 

Perhaps their most recognisable trait, their spines, are in fact toughened hairs protecting them from predators. Those ‘spines’ also double us as a thermoregulatory mechanism, lying flat to trap in heat and standing up to release it. Beneath these spines, a layer of dense fur keeps them insulated. 

Their snout is equally extraordinary. Packed with electroreceptors, it helps them detect ants and termites even in the dark. With a near-bottomless appetite, they are formidable foragers. And when it gets too hot, they’ve found their own solution. Unlike other mammals, echidnas can’t sweat or lick themselves to cool down so instead they have learnt to blow moisture bubbles from their nostrils to lower their body temperature. 

Along with their burrowing habits, these traits have helped echidnas survive icy temperatures, formidable predators and scorching fires. 

Ecosystem Engineers 

Not only are echidnas a window into the evolution of mammals and a beloved icon of Australia’s landscapes, but they are essential to the health of our ecosystems. Echidnas digging habits make them the ecosystem engineers of our soils, turning over nutrients and increasing water filtration to keep soil healthy and fertile. Being Australia’s most widespread mammal (reference), they are responsible for the health of countless ecosystems. 

Unchartered territory  

Despite their adaptability over thousands of years of shifting climates and terrain, the challenges echidnas face today are potentially some of their greatest yet.  

Sadly, the echidna’s fascinating survival traits are no match for the cars on the road, rapid clearing of land and the introduction of our pets. Echidnas rely on fallen logs and understory vegetation for foraging, breeding and regulation of their temperature - with increasing land clearing they are losing this vital habitat. As the urban sprawl encroaches on their habitat, and factors such as droughts force them to venture into new home ranges, more interactions than ever are taking place between echidnas and humans. Echidnas being hit by vehicles and attacked by pets are the leading causes for people reporting them to our service. 

In the past 12 months Wildlife Victoria has received over 1850 reports of echidnas needing our help. Reports of sick, injured, orphaned or displaced echidnas have grown by 230% in the past 5 years. Just last year those reports grew by 72% in comparison to 2023. 

Echidna populations might not be considered vulnerable in Victoria, but this is a concerning increase. It is understood that at one time Australia would have been home to three different echidna species, we are now left with just one. Protection of echidna habitat, road awareness and control of our pets is imperative to keep healthy populations of echidnas in Australia. In a world with increasing environmental challenges these resilient animals can be a window to the evolution of our ecosystem as we know it and perhaps how it will cope in the future.