You Are Hot Trivia Quiz

Answer: Crepuscular

Crepuscular is the term used for animals which are active only dusk and dawn. Nocturnal refers to animals active at night, and diurnal for those active during the day. Crepuscular behavior is itself divided into matutinal (animals which are active only at dawn) and vespertine (active only at dusk).

Dozens of animals are crepuscular, even those which don't live in the desert. Many species of insects, as well as mammals such as deer, rabbits, large cats, and most rodents, are active mostly during the cool time of day. In the desert, this allows an animal to sleep through most of the hot part of the day and search for water and food when it's cooler.

Answer: Uric acid

When animals metabolize amino acids, the building blocks of proteins, one end product is often ammonia, NH3. Unfortunately, ammonia is extremely toxic, and if it builds up in the body, the animal will die. Therefore, excreting nitrogenous waste is one fundamental adaptation of animals, and the ability to excrete uric acid is vital for the survival of many organisms which live in arid climates.

Fish have no trouble excreting pure ammonia, as their marine habitat heavily dilutes the weak base so that it can be released freely. This takes very little energy. Humans and other mammals, however, don't have access to enough water for us to excrete nitrogen in the form of highly diluted ammonia. Instead, metabolic processes in the human liver transform the ammonia into a compound called urea, which is much less toxic. Urea is mixed with water to form urine, which is then excreted.

Desert animals, though, have a bigger problem: they don't have access to enough water to safely excrete their nitrogenous waste as urine. Doing so, they could easily dehydrate. Instead, many birds and reptiles, particularly those which live in warm climates, remove the toxic substance in the form of uric acid, a solid, nontoxic compound. Uric acid is easily excreted with very little water. The drawback is that extensive metabolic processes are required to transform the ammonia into uric acid, and that requires energy. The sacrifice of energy for water is what allows desert animals to live. Humans produce uric acid too. When the kidneys break down, it builds up in the bloodstream, possibly resulting in kidney stones, or even a painful form of arthritis called gout.

Answer: The local mud pit--nothing like mud to protect from the Sun

What do elephants and pigs have in common? They like to roll around in the mud! Mud acts as a cooling agent, similar to water. Because an elephant's skin is heavily wrinkled, the mud gets caught in it and dries, keeping the elephant cool even after it leaves the mud pit. There's also evidence to suggest that mud serves as a fairly effective sunblock, and it helps keep away insects.

Pigs, elephants, and rhinos may use mud to keep cool, but other animals resort to different techniques. Hippopotamuses secrete a red liquid that serves as a natural sunblock. This is far better than the fate doled out to another class of large mammals. Some marine biologists have discovered that several whales congregating in the Gulf of California are in fact suffering from sunburn, blamed on a growing hole in the ozone layer. Perhaps the whales should cover themselves in the oceanic equivalent of mud?

Answer: Panting

Birds don't have sweat glands, so to cool off, they have two main strategies. Birds have a special membrane in their mouths which they can rapidly flutter back and forth. This can help cool off the airways and promote the evaporation of water in the throat. If you see a bird on a hot day walking around with its mouth open, there's a fairly good chance that it's trying to cool off. Other birds pant. This behavior, also seen in dogs, essentially tries to expel hot air inside the animal as rapidly as possible.

One interesting avian adaptation to the heat is seen in none other than the toucan. The toucan's large beak promotes heat exchange with the environment, and on a hot day, it can increase the amount of heat flowing to the beak, expelling the heat more quickly.

Answer: Large body surface-area-to-volume ratio; pale-colored body

A pale-colored body works the same for animals as it does for humans wearing light-colored T-shirts. Light colors tend to reflect more light than dark colors, so less sunlight is absorbed, and the organism stays cooler. At the risk of sunburn, few desert animals are actually pure white, but a pale-brown color is fairly common.

Surface area is important too. The greater an organism's surface area, the more it will exchange with its surroundings: heat and nutrients. Organisms in cold climates are often large and compact. On the contrary, many animals which live in warm areas are small and have protuberances on their bodies to maximize the amount of space in which heat can escape. The amount of energy which radiates for a given body surface area is greater in animals which live in warm climates.

This concept is mathematically modeled by Allen's Rule, named for an American zoologist from the 20th century. Allen found that appendages were often larger for dwellers of warm climates, even among human races. Anatomically, the Inuit generally have shorter arms and legs, but broader bodies, than their counterparts who live in more hospitable climates.

Answer: When water evaporates, the water molecules which are left have less energy and are "cooler."

The evaporation of water molecules, or their surface transformation from liquid to gas, results in a useful phenomenon called "evaporative cooling", which is the main impetus for sweating. Water's chemical structure causes it to have a high latent heat--that is to say, it requires a lot of energy to evaporate water, compared to other liquids. Thus, heat energy goes into evaporating the water, rather than raising body temperature. Also, because warmer surface water molecules will evaporate first, they leave behind the cooler water molecules. This has the net effect of cooling the body.

Sweating isn't unique to humans, but only some mammals can do it. Horses will sweat, particularly in response to exercise. Dogs and cats only sweat through their feet, forcing them to resort to other methods to keep cool.

Answer: Their ears

Jackrabbits don't only have large ears. They also have control over the blood vessels spanning their ears. Effectively, when it's warm, they dilate their blood vessels, increasing blood flow to the organs. Body heat flows into the ears, which are large and thin, and therefore have a high surface area-volume ratio. As we've already seen, this results in more heat transfer with the environment, and cools the rabbit down.

Other animals with adaptations like the jackrabbit's include the fennec fox, and, interestingly enough, the elephant.

Answer: Vulture

If you think that secreting a slippery, salty substance to cool down is slightly gross, then don't look at a turkey vulture when it heats up. Vultures, as well as some storks and condors, use an adaptation called urohidrosis, which, like sweating, relies on evaporative cooling. However, the substance being evaporated is, well, excrement.

Vultures are generally not known for their cleanliness, as they feed on carrion and regurgitate it to feed their young. However, some biologists suggest that urohidrosis allows the vulture to clean off bacteria living on its legs. So perhaps the disgusting habit is actually designed to be sanitary!

Answer: Kangaroo rat

Kangaroo rats are so named because they are bipedal and hop around in a way highly reminiscent of actual kangaroos. However, their skill at water preservation is far more fascinating. In fact, when offered water in captivity, kangaroo rats sometimes refuse to drink it. They absorb all of their water from consumption of dried-out seeds, which they hoard in their burrows. They can use metabolic pathways which create water, rather than usable energy, from food. The rodents' burrows are small, and often, sealed up. This allows the rats to reabsorb the moisture in the air created when they exhale, limiting the amount of water lost even through breathing.

Living in the Western United States (predominantly, the Sonoran and Mojave Deserts), kangaroo rats rarely grow to more than a foot in length. They can live for several weeks without drinking water.

Answer: Aestivation

Aestivation (or estivation in American English), is a phenomenon common in some snails, crabs, reptiles, amphibians, and fish. It essentially is hibernation during summer months. The animal enters a state of suspended animation, lowering its heart and metabolic rates, and rarely moving.

The fat-tailed dwarf lemur, an inhabitant of Madagascar, has been shown to undergo a form of aestivation as well, making it nearly unique amongst mammals. Some lungfish native to Africa also go into torpor when water runs out during hot summers.