Dogs. Birds. Elephants. Squirrels. You. Have you ever wondered how animals stay cool in the summer?
Much research has been done to undercover the fascinating variety of ways in which animals accomplish keeping the heat at bay. Some animals have heat-beating habits they engage in. Some animals choose to relocate from the heat. Some animals are so evolutionarily adept at dealing with the heat that they do not even use habits, but the benefit of evolution.
Here are some select animals and their different methods for staying cool.
Though horses are so unlike us humans, they have one similar key feature: they sweat. The act of sweating itself does not cool animals down, but the ensuing “evaporative cooling,” where the sweat beads carry away heat with them.
Chimpanzees, sharing about 98% of their DNA with humans, also have a high sweat gland concentration (along with relatives such as gorillas, baboons and spider monkeys). Other animals that beat the heat with sweating include donkeys and zebras.
There are also small alternatives to sweating. Dogs, for example, do sweat, but only through their paws. To create additional cooling, dogs pant. Panting is more than just a cute thing they do after playing, because it has the very practical function of evaporative cooling at a stronger rate than sweating.
When you see your dog looking fatigued and panting, it’s not because they’re “tired,” but simply because the rapid inhalation and exhalation of air humidifies it, which increases the rate of evaporation, cooling down their bodies.
Some animals release heat without utilizing humidity or evaporation, but simply by changing blood flow internally. A simple and effective method, vasodilation is where blood vessels expand, increasing their diameter to allow more blood flow close to the skin's surface. This increased blood flow creates more heat loss, often resulting in a flushed look (this is why your skin turns red when very active).
Some animals like elephants and jackrabbits use their ears as the surface from which to release the heat because their ears have a greater surface area and are also (in the case of elephants) very thin.
Elephants, indigenous to very hot climates, also use their trunk to spray themselves down with water. Fennec foxes, in addition to using their large ears to listen for prey, also release heat via vasodilation.
Birds are among the most interesting animals for various reasons, but their cooling methods are especially unique. When it comes to staying cool, birds have two key evolved functions: gular fluttering and evaporative cooling.
“Gular fluttering” is the act of taking moist tissues in the throat and rhythmically vibrating them to increase the evaporation of the heat from a bird’s throat in a similar way to how we sweat to send heat away from the body.
Birds’ version of evaporative cooling is far more strange to humans; many birds, like storks and vultures, will defecate on their legs so that the predominantly liquid feces can then evaporate, taking unwanted heat with it.
Estivation—the opposite of hibernation—is a practical concept, but not just any species can do it; animals that participate must be equipped in the same way animals are that hibernate, with a naturally-lowering metabolic rate to sustain them through months of dormancy.
During estivation, heart rate and breathing rate also slow down to prevent extra energy expenditure, but estivation does put animals in a lighter state of dormancy than hibernation, so they are able to “wake up” more quickly despite the changes to the body. Animals that estivate include desert tortoises, some hedgehogs, snails, crocodiles and even some fish like African lungfish.
Some animals, not evolutionarily equipped for heat, are practical in their approach to scorching days. Lots of mammals will simply shed hair to ward off unwanted heat.
Ground squirrels can flip their own tails over their bodies and heads to shield themselves from the sun. Pigs, not able to sweat, will purposely spend more time in the mud, an act called “wallowing.” They will also increase their water intake during hot times of year.
Lizards, snakes, turtles and even some domesticated animals like cats will simply lie low during the hottest parts of the day (pigs do this as well). Bearded dragons open their mouths to cool down and regulate their temperature. This is called gaping.
Apart from your natural functions of sweating (evaporative cooling) and vasodilation, what do you like to do to beat the heat? Try out this simple DIY activity at home to better understand evaporative cooling.
Too hot outside? You can also try this more complex one to make your own swamp cooler.
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