Meet animals who like extreme heat

By Dr. Beth Leermakers

Some like it hot! Well, maybe animals don’t enjoy extreme heat, but some species are well adapted to tolerate it. Here are a few animals whose physical characteristics and behaviors protect them from scorching heat. 

Camels

Known as “ships of the desert,” camels can survive temperatures as high as 120° F. These hardy creatures live in the most extreme places, such as North African deserts, the Gobi Desert, the Middle East and Australia. Camels have several adaptations that make desert life possible:

Water retention. Camels can drink 32 gallons (yes, gallons!) of water at once and survive for one week without water. When water is scarce, camels can’t afford to lose precious moisture through sweating or breathing. Camels’ body temperature ranges from 93 °F to 107 °F, so they don’t need to sweat very often. The spongy bones in their noses absorb excess moisture to retain every drop of water, so the air they breathe out is dry air. 

Multi-purpose humps. Humps store fat (not water), providing energy reserves when food is scarce. Camels can go for several months without food. Humps also help camels with thermoregulation (i.e., maintaining their body temperature) by releasing heat on hot days. 

Heat protection. Leathery, heat resistant feet, knees, elbows and sternums keep them from burning when camels lie on the sand. Their coats provide some insulation, protecting them from the heat.  

Pompeii Worms

Pompeii worms are extremophiles — animals that survive and even thrive in physically extreme conditions that are harmful to most life on Earth. Named after the Roman city (Pompeii) that was destroyed during an eruption of Mount Vesuvius in AD 79, Pompeii worms live in the Pacific Ocean at depths of 5,000-10,000 feet. These 5-inch-long worms live in tubes near extremely hot, mineral-rich hydrothermal vents that form near undersea volcanoes. 

Pompeii worms thrive at temperatures up to 176° F, making them the second most heat-tolerant complex animal known to science (after the tardigrades or water bears). 

Pompeii worms keep their heads in cooler water (72° F), while their tails are exposed to hot water. Scientists don’t know exactly how these creatures tolerate the scalding water. A centimeter-thick layer of fleece-like bacteria on the worm’s back may have special proteins that protect the worms from the heat. The bacteria may also provide thermal insulation. Studying the worms is difficult because they have not survived decompression (when brought up to the ocean’s surface). 

Somali Wild Asses

Somali wild asses are the smallest members of the Equidae family that includes horses, zebras and asses. Native to the rocky desert of eastern Africa, Somali wild asses are built to withstand extreme desert heat. A wild ass can lose almost one-third of its body weight in water and survive. 

Their large ears help them disperse heat. Somali wild asses graze in the early morning hours, then rest under any shade they can find until the temperature drops in the late afternoon and evening. 

The wild ass evolved to hoard resources instead of mates. A solitary stallion (adult male) will guard a watering hole and mate with any females that show up to drink. 

The Somali wild ass is Critically Endangered (i.e., at high risk for extinction), with only a few hundred left in their native habitat. A drought could wipe out the entire population. Protected by the local government, Somali wild asses are still hunted for meat or for their fat, which is used for medical treatment and is believed to cure hepatitis.

Desert Tortoises

Desert tortoises are found in the Mojave and Sonoran deserts of southwestern North America. These reptiles have several adaptations to beat the heat and survive with limited water intake:

Going underground and shutting down. Desert tortoises use their strong forelimbs to dig three- to four-foot-deep burrows that are up to 32 feet long. Tortoises spend up to nine months per year in burrows, entering a form of reptilian hibernation in the winter. 

During the hot, dry summer months, tortoises spend up to 95 percent of their time in their burrows. They enter a state of inactivity (called estivation) that allows them to conserve energy and water. In the cooler months of autumn and spring, when plants are growing, desert tortoises emerge from their burrows to eat and drink. Tortoises can go for up to one year without access to fresh water, getting the water they need from plants. 

Water retention. Desert tortoises’ slow, lumbering walk helps them reduce water loss. Sealing their legs and head into their shell also retains fluid. Tortoises reabsorb water from their bladder to rehydrate. 

Although I complain about the Texas heat, I’m grateful that I don’t live in a desert burrow or have to go a week without water!