How Do Animals Keep Cool?

By Katherine Spada

Billy the Asian elephant splashing in one of the habitat's pools.

Sweating

Primates, including humans, apes, and monkeys, sweat profusely when overheated. When we sweat, and it evaporates from our skin, it carries heat away from our bodies. Some biologists theorize that animals who sweat as their primary method of cooling down, have the advantage of being able to run longer distances at faster speeds. Perhaps this is why horses are one of the few non-primate animals that perspire profusely.

Chimpanzee chilling. Photo by Jamie Pham.

Mud

You’re probably familiar with the image of a pig rolling around in a mud bath. It’s not because these animals aren’t clean, it’s because coating their skin in mud helps protect it from sun exposure, as well as provides a slow release of water through evaporation.

The red river hog, looking more like a red & brown river hog. Photo by Jamie Pham.

Urohidrosis (a.k.a. Peeing/Pooping)

If that wasn’t dirty enough for you, some birds, including vultures and storks, “evacuate” onto their own legs and feet. Just like sweat evaporating off our skin, when the liquid in these birds’ excrement (a combo of urine and feces released as one) evaporates off of their scaly extremities, it lowers their body temperature.

Even seals may urinate on their hind flippers to take advantage of the cooling effect of evaporation!

"Gotta go!" —The Cape vulture, probably. Photo by Tad Motoyama.

Spit

Yes, more examples from the animal kingdom about using bodily fluids to encourage cooling down by way of evaporation! Kangaroos’ forearms have lots of blood vessels near the surface of their skin. So, when the weather’s hot, they lick this part of their arms so their saliva can make them cooler. (Try putting a cold washcloth on your wrists or the insides of your elbows the next time you feel overheated; it will cool you down quickly!)

Suggested beverage pairing to go with browse? Saliva. Photo by Jamie Pham.

Black & White Stripes

There are conflicting opinions on this one, but some scientists have suggested that the purpose of a zebra’s stripes is more for thermoregulation than it is for camouflage. Black absorbs light, converting it to heat, and white reflects light, absorbing heat at a slower rate. Air currents flowing over these two colors at different speeds could create a sort of microclimate just above its skin, almost like a built-in breeze. Pretty helpful for an animal that spends more time in the hot sun grazing than other prey animals which don’t have stripes.

Groovy Grevy's zebras have narrower stripes than other zebra species. Photo by Jamie Pham.

Blood Sweat

While this sounds like it could be the name of a heavy metal band, it’s actually a misnomer for the substance that hippos secrete from glands in their skin to create a sunscreen barrier. Like zebras who spend a lot of time grazing out in the open, hippos need protection from the sun. But as large animals that spend a lot of time submerged underwater, a protective coat of hair or fur wouldn’t be as useful as the oily red substance they produce.

Mara the hippopotamus in her element. Photo by Jamie Pham.

Gimme Shelter

Smaller reptiles’ bodies are very sensitive to even subtle changes in the outside temperature, which can quickly impact their metabolism. Lacking some of the thermoregulating mechanisms common to mammals, often the best course of action for small lizards is to relocate under a rock, or into the shade offered by vegetation.

If it stays very still, the horned lizard could almost blend into the background. Photo by Jamie Pham.

Big Ears

Some desert-dwellers’ big ears are used to help them regulate their body temperature. With a large web of blood vessels just under the skin, ears can release heat from an animal’s body without sacrificing precious water by sweating.

My, what big ears the fennec fox has! Photo by Jamie Pham.

Panting

We’ve all seen canines do this, but how exactly does it help them cool down? When dogs quickly inhale cooler air and exhale hot air, it reduces their body temperature from within, starting with their throat and lungs.

The African wild dog looking like more of an African mild dog. Photo by Tad Motoyama.

Swimming & Splashing

Many, many animals like to play in cool water if it’s available. Cold water drains body heat 25 times faster than cold air, which makes a cool pool on a hot day the next-best thing to A.C.

Billy the Asian elephant sucking up a trunk-full of water to drink or splash on himself. Photo by Jamie Pham.

Plan(t) Ahead

Succulents have many special, often beautiful features that enable them to survive in arid conditions. Their fleshy tissues are distinctive and enable them to store water through long dry spells. Many succulents also feature armament (such as spines and teeth) to protect their water stores from thirsty animals, surface fuzz or wax that act as sunscreen to reduce evaporation (the plant version of sweating), and camouflage adaptations that help them hide from creatures who might want to consume them. 🌵

The Baja California bird garden at the L.A. Zoo. Photo by Jamie Pham.