When temperatures rise, organisms must manage internal body heat, a process known as thermoregulation. Sweating is one cooling strategy, where the body releases water onto the skin’s surface, and its evaporation dissipates heat. While humans are well-known for this ability, it’s not universal; many animals employ diverse methods to maintain stable body temperature.
Animals That Sweat Like Humans
Beyond humans, some animals also sweat for cooling. Horses, for instance, are among the few mammals that sweat profusely over most of their bodies, using a system comparable to human eccrine sweat glands. Their sweat, containing water, electrolytes, and proteins like latherin, spreads across the skin to enhance evaporative cooling. This protein helps sweat spread evenly, making the cooling process more effective. Horses can lose several liters of sweat per hour during strenuous activities, highlighting this mechanism’s importance for their thermoregulation.
Some primates, including chimpanzees and Old World monkeys, also possess eccrine sweat glands, enabling them to sweat for cooling. While their sweating capacity isn’t as extensive or efficient as humans (due to thicker fur or lower gland density), these primates still use this method to regulate body temperature. The presence of these glands suggests an evolutionary adaptation to warmer climates, allowing for evaporative heat loss.
Beyond Human-like Sweating
Not all bodily secretions are for whole-body cooling; some animals have specialized glands with different functions. Dogs and cats possess eccrine sweat glands, but these are mainly concentrated on their paw pads. While this localized sweating offers minor cooling (especially in cats), its primary roles include providing traction or leaving scent markers. Their fur-covered bodies make widespread evaporative cooling through sweat impractical.
Hippopotamuses offer another unique secretion often mistaken for sweat. They produce a reddish-orange fluid, commonly called “blood sweat,” though it is neither blood nor true sweat. This oily substance, containing hipposudoric and norhipposudoric acids, acts as a natural sunscreen and an antiseptic. It protects their skin from UV rays and helps prevent infections, a crucial adaptation for animals spending significant time exposed to sun and water.
Other Ways Animals Stay Cool
The majority of animals rely on diverse strategies beyond widespread sweating to manage their body temperature. Panting is a common and effective method, particularly for many mammals like dogs and various bird species. This rapid, shallow breathing increases airflow over moist surfaces in the respiratory tract, such as the tongue and lung lining, facilitating evaporative cooling.
Wallowing is another behavioral adaptation observed in animals like pigs, rhinos, and elephants. By rolling in mud or water, they coat their bodies, which then cools them as the moisture evaporates. This also offers protection from sunburn and insects. Some birds engage in gular fluttering, a rapid vibration of the moist membranes in their throat, which promotes evaporative cooling without requiring large muscular movements.
Behavioral adjustments are widespread, with many animals seeking shade during the hottest parts of the day, burrowing underground, or becoming active primarily at night (nocturnal behavior) to avoid extreme heat. Physiological adaptations also play a role, such as vasodilation, where blood vessels near the skin surface expand to increase blood flow and release heat to the environment. Specialized circulatory structures like the rete mirabile, a network of blood vessels, can also facilitate heat exchange, helping to cool specific body parts or conserve heat. Some animals, like kangaroos and certain rodents, spread saliva on their limbs, using its evaporation to cool down.