How Animals Beat the Heat: Unique Ways They Stay Cool

Hippos are known for wallowing in mud, but did you know they also have a natural form of sunscreen? Hippos secrete two compounds—hipposudoric acid and norhipposudoric acid—that coat their skin and protect them from the sun's harsh rays. These compounds bind to mucus and help them stay in place on the skin, even when the hippos spend hours in the water. Not only does this act as a sunscreen, but it also seems to repel insects. Researchers are still studying how exactly these compounds work, but they play a significant role in keeping the hippos cool under the scorching sun.

Many people are familiar with dogs, cats, or horses panting when they’re hot. But panting isn’t just a random act—it’s a natural cooling mechanism. Panting works much like sweating in that it relies on the process of evaporation. When animals pant, they exhale hot air from their lungs, and the water vapor that evaporates from their mouths helps to cool them down. When they inhale, they take in cooler air, further aiding in the cooling process. Since panting relies on moisture, it does require a good amount of water, which is why animals can easily get dehydrated in hot weather.

While panting is the main method of cooling down for many animals, some animals have an additional cooling technique: sweat glands on their paws. Animals like dogs, cats, and small mammals have sweat glands on the underside of their paws. These glands help provide friction between the paw and the ground, which is necessary for walking and running. However, while their primary function is not thermoregulation, the sweat from these glands can provide a minor cooling effect as a secondary benefit.

Birds are another group of warm-blooded animals that lack sweat glands. But that doesn’t mean they don’t have ways of staying cool. Some birds, such as pelicans, herons, and owls, use a method called gular fluttering. This involves vibrating the muscles and bones in their throat, which exposes the moist area to the air. This helps to increase evaporation and cool the bird’s body temperature. This process is highly efficient because it doesn’t require a lot of energy and is a great way for birds to regulate their body heat.

While some animals take a break from the cold by hibernating, others deal with the heat by sleeping through it. This process is called estivation, and it helps animals conserve energy during extremely hot periods. Animals like snails, lungfish, and earthworms can all enter a state of dormancy when the heat becomes too much to handle. In this state, their metabolism slows down, and they don’t need to eat as frequently. Some animals like snails even have protective shells to retreat into, while others like lungfish burrow into the ground to escape the sweltering temperatures.

Sometimes the best way to stay cool is simply to avoid the heat altogether. Reptiles are experts at regulating their temperature by seeking shade. They move into the sun when they need to warm up and retreat to cooler, shaded areas when they need to cool off. However, because reptiles don’t have internal mechanisms to regulate their body temperature, they are particularly sensitive to extreme weather changes. When temperatures become too high, reptile populations may decrease because they’re unable to hunt or reproduce properly.

As humans, we’ve created the air conditioner, but animals like termites, bees, and prairie dogs have been using their forms of “air conditioning” for centuries. Termite mounds, which can grow several yards tall, are equipped with tiny holes that create a system of air pockets. These pockets allow for air circulation and cooling through convection. Similarly, bees use water to cool their hives by fanning it with their wings. Prairie dogs have intricate burrow systems with a small tower placed higher than the other entrances. This allows for a breeze to circulate, pulling warm air from the burrows and keeping the space cool.

Though many animals have unique ways of cooling off, some use less pleasant methods. Storks, herons, and vultures, for example, use their excrement to help cool off. These birds defecate on their legs, and because bird excrement is mostly liquid, it works similarly to sweat. The evaporation of the liquid helps to pull heat away from their bodies, allowing them to stay cooler under the hot sun.

Australia is one of the hottest continents, and its wildlife has developed some incredible methods of staying cool. Kangaroos, for example, have a cooling technique that’s similar to that of the storks and vultures. Instead of defecating, kangaroos spit on their arms. Their forearms have a network of blood vessels that help cool their bodies. They wet the area by licking or spitting on their arms, and as the spit evaporates, it cools them down. This effective cooling strategy helps kangaroos survive the scorching heat of the Australian outback.