once believed lethal to the species
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Short-beaked echidnas roam across Australia in conditions once considered impossible for their survival.
Early laboratory research suggested temperatures beyond 35 degrees Celsius should kill these ancient monotremes.
Yet echidnas persist through summers where ground temperatures climb past 47 degrees Celsius.[1]
Curtin University researchers have now explained this apparent contradiction using thermal imaging technology.
Wild echidnas were filmed blowing bubbles of mucus that burst and wet their beak tips. As the moisture evaporates, it draws heat from blood vessels, cooling the animal from the nose down.[2]
An echidna's beak contains a large blood sinus, a reservoir where blood pools close to the surface. This vascular structure gives the mucus bubble mechanism its cooling power. Once the bubble bursts, evaporating moisture pulls heat directly from that blood supply.[3]
Monotremes such as echidnas cannot sweat, pant or lick themselves to shed heat. These common mammalian cooling strategies are absent from their evolutionary toolkit entirely. Researchers say this absence made the mucus bubble discovery especially significant.[4]
Evaporative cooling works because turning liquid into vapour requires energy drawn from surrounding heat. When bubble moisture evaporates from the beak tip, it extracts thermal energy from nearby tissue. That process lowers the temperature of blood circulating through the vascular sinus.[2]
Thermal imaging showed echidnas begin blowing bubbles once their body temperature rises alongside rising ambient heat. Dr Christine Cooper, the study's lead author, described the response as automatic under thermal stress. The behaviour intensifies as environmental temperatures continue climbing toward dangerous extremes.[4]
Echidnas complement bubble blowing by pressing their spineless bellies against cool, moist ground. Spines cover most of an echidna's body and function as flexible insulation. Bare skin on the underside and legs works as an additional thermal window.[5]
During extreme heat, echidnas retreat into burrows, hollow logs and spaces beneath buildings. Some individuals seek out birdbaths, rivers, and beaches for direct cooling. These shelters buffer animals from radiant heat during the hottest parts of the day.[4]
Foraging activity shifts substantially once temperatures spike beyond comfortable thresholds. Echidnas that forage by day switch toward dawn, dusk and overnight activity instead. This nocturnal shift reduces heat exposure while animals continue searching for ants and termites.[4]
Keeping the nose moist also supports electroreception, the sense echidnas use to detect buried prey. Moist nasal receptors detect faint electrical signals from insect muscle contractions underground. Bubble blowing therefore serves cooling and feeding functions simultaneously, a dual-purpose adaptation.[3]
Curtin scientists used non-invasive infrared thermography cameras to carefully study echidnas without disturbing natural behaviour. This non-contact technology captured surface temperature patterns across the animals' bodies. Researchers filmed wild short-beaked echidnas in bushland roughly 170 kilometres southwest of Perth.[2]
The team recorded 124 wild echidnas at least monthly across a full year of fieldwork. Surrounding air and ground temperatures were logged alongside each animal's thermal profile. Beak tips consistently registered as the coolest surface, while ears ran hottest.[1]
Scientists previously assumed 35 degree heat was lethal based on controlled laboratory experiments. Those early studies lacked field observation of echidnas coping with real environmental extremes. Wild populations clearly exceeded laboratory predicted limits across multiple Australian regions and seasons.[3]
Studying wild echidnas presents persistent challenges because the animals are cryptic and solitary. Their nocturnal habits during heatwaves make daytime observation increasingly difficult for field researchers. Thermal cameras offered a practical solution, capturing physiological data without handling stressed animals.[2]
Research into a 2015 prescribed burn found echidnas tolerate shelter temperatures between 35 and 40 degrees Celsius. That tolerance holds for periods of roughly ten hours before physiological strain increases. Beyond that threshold, researchers warn the cooling mechanism faces genuine failure risk.[6]
Consecutive heatwave days compound physiological stress far beyond single hot afternoons. Echidnas rely on overnight cooling to recover from daytime heat exposure. Extended heatwaves without cooler nights erode this recovery window and heighten mortality risk.[6]
Low humidity generally accelerates evaporation, making bubble cooling more efficient during dry heat events. However, dry conditions also increase moisture loss, forcing echidnas to blow bubbles more frequently. This trade-off links cooling efficiency directly to hydration availability across the landscape.[6]
Longer, more frequent heatwaves under climate change could still strain echidna resilience over time. Population monitoring across most Australian states remains limited, according to conservation researchers tracking the species. Without baseline data, authorities cannot properly measure how populations respond to intensifying heat.[7]
Entering torpor allows echidnas to survive bushfires by sheltering underground or within hollow logs. Body temperature drops substantially during torpor, reducing metabolic demand while flames pass overhead. Researchers studying a Western Australian prescribed burn found nearly every tracked echidna survived.[6]
Despite surviving direct flames, echidnas face serious starvation risk once fire passes through their territory. Burnt landscapes offer little food, forcing animals to extend torpor for weeks afterward. Researchers recorded reduced activity and lowered body temperature lasting up to three weeks post-fire.[6]
Underground shelters moderate the extreme heat generated by fast moving bushfires above the surface. Soil provides insulation, keeping burrow temperatures within the tolerable 35 to 40 degree range. One tracked echidna died after sheltering in a log that later caught fire.[6]
Heatwaves and bushfires increasingly overlap under a warming climate, compounding pressure on echidna populations nationally. Citizen science projects have emerged partly because formal government monitoring remains patchy across most regions. Closing this data gap is essential for assessing long term species resilience.[8]
Echidnas demonstrate remarkable physiological ingenuity, surviving conditions once assumed fatal for the species. Bubble blowing, sheltering, torpor and nocturnal foraging together form a layered defence against Australian heat extremes. This investigation shows science overturning decades of flawed laboratory assumptions about a resilient native mammal.
These adaptations still carry limits worth serious attention from policymakers and land managers alike. Compounding heatwaves and bushfires under climate change threaten to overwhelm even well evolved survival strategies across the continent.
Investment in consistent, nationwide population monitoring remains scarce outside a handful of well studied regions. Without accountable, sustained research funding, Australia risks losing insight into a species now facing an increasingly uncertain climate future.
References
1. Echidnas Blow Bubbles of Snot to Stay Cool in The Australian Outback Reports Curtin University thermal imaging findings on wild echidna body temperatures against extreme ground heat.
2. Study finds blowing bubbles among echidna's tricks to beat the heat Curtin University media release detailing Dr Christine Cooper's Biology Letters research on echidna thermal windows.
3. Prickly echidnas stay cool by blowing snot bubbles Explains the beak's blood sinus anatomy and the dual cooling and electroreception function of moist nasal tissue.
4. Echidnas blow snot bubbles to cool down Covers monotreme physiology, shelter seeking behaviour and expert commentary from Australian echidna researchers.
5. Echidnas blow snot bubbles to stay cool Details how echidna spines insulate the body while spineless areas function as heat exchange windows.
6. Cool echidnas survive the fire Peer-reviewed study documenting echidna torpor, burrow temperature tolerance and post-fire recovery after a prescribed burn.
7. EchidnaCSI: Engaging the public in research and conservation of the short-beaked echidna Outlines Australia-wide gaps in formal echidna population monitoring and the citizen science response.
8. Echidna Conservation Research Australia Research group documenting the absence of baseline population data across most Australian states and territories.
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