How do you beat the heat? Do you fan your face? Hop in the pool? Linger in the frozen veggie aisle?
Australian animals have evolved some weird and wonderful ways to survive heat stress and times of drought. From brain-sucking to spit-bathing, here are seven animals that keep their cool.
Mulgaras: delightfully deceptive
Awww. Looks cute, doesn’t it? It sucks the brains from its prey.
The mulgara (Dasycercus spp.) lives in central Australia, where seasons cycle from ‘boom to bust’ and back again. In the good times, mulgaras store excess fat in their chubby little tails. When food is scarce, they draw on the fat from their swollen tails to survive. Best of all, this carnivorous marsupial doesn’t need to drink water. It’s a fierce predator that meets all of its water requirements from eating juicy mammals, reptiles, centipedes, spiders and insects. The delightfully deceptive mulgara.
Zebra finches: fat busters to the fore!
Zebra finches can ‘drink’ water from their own fat. Huh?
During a drought, zebra finches (Taeniopygia castanotis) quench their thirst by breaking down the fat in their own bodies. Most birds can break down muscle or other proteins to get water, but they also need these proteins to fly and to keep their little hearts a-tickin’. So, if a heat-stressed bird converts too much protein it can do them more harm than good.
Researchers from Jagiellonian University in Poland discovered that, during a simulated ‘drought day’ a typical zebra finch – which weighs a tiny average of 13.5 grams – produced about 0.44 gram of water by breaking down body fat. Freeing up this much water using only protein would require one-third of the zebra finch’s flight muscles, or an amount three times the mass of their hearts. Clever, fat-busting finches.
Researchers from Curtin University discovered that zebra finches are also able to predict high temperatures. This means they can pre-emptively feed and drink in preparation for heatwaves. They can also avoid or limit their movement during the hottest parts of the day. Now that's a technique we can learn from!
Thorny devils: finding the dew in the dry
The thorny devil (Moloch horridus) can drink with its skin. Sorry, what?
This ant-eating lizard lives in arid Australia, where pooled water is rare. But, during the night, dew condenses on its spiky body, and in the morning it brushes up against dew-covered grass. Then, the devilish magic happens! Its scales are arranged so that dew channels down to the corners of its mouth. The grooves between its scales are hygroscopic (moisture-attracting), so it absorbs water like blotted paper. It then moves moisture to its mouth via capillary action. Genius! The same process occurs if it rains. But if it’s extremely dry, they can bury themselves in sand, and draw moisture from it. What a crafty devil.
Crucifix frogs: cocooned from thirst
Feeling a little parched? Why not wrap yourself in a mucus cocoon and bury yourself underground ’til it rains again?
The crucifix frog, or holy cross frog, (Notaden bennettii) has life in arid Australia sorted. It spends most of its life underground, enveloped in a home-made, protective mucus cocoon. It can stay like this for years on end, dormant, patiently waiting for rain. And when rain eventually does trickle down, it eats its own cocoon for a nutritious kick start – delicious! – and starts digging skywards.
Bilbies: radiating heat
My, what big ears you have! All the better to stay cool.
Bilbies (Macrotis lagotis) have big ears, it’s plain to see. This desert-dwelling marsupial uses their ears like a radiator. Their ears have such a large surface area, and are so loaded with blood vessels, that the blood that flows through them returns to their bodies cooler than before. This lowers the bilbies overall body temperature.
Echidnas: it's snot easy to cool down
The echidna nose how to stay cool, and its snot the method you'd think.
Short-beaked echidnas (Tachyglossus aculeatus) don't have sweat glands, nor do they pant or lick themselves. Until recently it was thought that they were bad at dealing with the Australian heat.
However, in early 2023, researchers from Curtin University published results from studying thermal vision of wild, short-beaked echidnas in bushland. They found that echidnas blow bubbles from their nose, which burst over the nose tip and wet it. As the moisture evaporates, it cools them down. Their spines provide flexible insulation, retaining heat, so they also perform belly flops. They press their spineless bellies and legs down against cool surfaces.
Kangaroos: hopping for better times
When it comes to amazing adaptations, kangaroos (tribe Macropodini) punch above their weight.
Unlike mulgaras and thorny devils, kangaroos need pooled water to survive. But some species, like the red kangaroo, live in the driest parts of central Australia. During a drought, roos are known to dig holes more than a metre deep to get drinking water!
Hopping is a famously fast and efficient mode of locomotion. Kangaroos can reach speeds of 60 kilometres per hour, clearing over eight metres with a single hop! This allows them to cover large distances to find food and water in sparsely vegetated parts of Australia.
Another trick in their pouch involves taking a breather from parenthood. Female kangaroos normally give birth once a year. But what if it’s too dry, and there’s not enough food for her and her joey? All but three species of kangaroo and wallaby can pause their pregnancy and keep the embryo in a dormant state – also known as ‘embryonic diapause’. This gives the young the best chance of survival.
Finally, kangaroos don’t have sweat glands. Instead, they give their forelegs a refreshing ‘spit bath’ to cool down. Their forelegs have a special network of blood vessels, speeding the evaporative cooling process.
So, there you are. The next time you’re feeling hot and sweaty, why not dig a large hole and sit in it? Or give your mate a spit bath? Don’t thank us for this brilliant idea. Thank your favourite arid Australian animals.