Unless you are a spelling bee champion, you may not have encountered the word ‘estivation’ before. Estivation allows some animals to survive during hot, dry conditions. Here you will learn what estivation is, how it works, and which animals use it.
Definition of Estivation
Have you ever seen your laptop, phone or tablet screen go dark after you’ve left it alone for a few moments? Our devices do this in order to conserve energy when we aren’t using them. Some animas in the wild ‘go dark’ in a similar way when they’re trying to conserve energy.
Only when they do it, it’s called estivation.Estivation, which is a form of dormancy, is about trying to minimize energy needs during tough times. There are actually several ways animals try to conserve energy when environmental conditions become extreme. Perhaps you’re most familiar with hibernation.
Animals such as brown bears hibernate in winter to escape a cold world where food supplies are certain to be low. They find a warm place to hide, reduce their metabolism, and let their body temperature plummet, all in the name of reducing their energy needs.Estivation is kind of similar, but instead, the animal is trying to survive the hot or dry conditions of a desert summer or the steamy heat of the tropics. Just like hibernation, the animal’s metabolic rate, heart rate, and breathing slows down, but instead of looking for a warm place, the animal tries to find a shady, cool place.
That often means going underground.There’s one other type of dormancy in animals. It’s a daily torpor. Usually a torpor dormancy is at night. Again, this is a way of saving energy, but in a torpor, the animal is dormant for less than 24 hours rather than the longer dormancies of a hibernation and estivation. Hummingbirds are especially known to temporarily reduce their insanely high metabolisms with a daily torpor.Surprisingly, despite the reasons for going dormant, whether it’s because of heat, cold or food supply, the way the body estivates, hibernates or goes into a torpor is a similar process.
It’s even possible that humans may be capable of a short hibernation. And I’m not talking about curling under a blanket in front of the TV in the winter. There have been some examples of people whose metabolism has slowed down dramatically during freezing conditions, and rather than freezing to death, they recover when they are warmed back up.
Examples of Animals That Estivate
Probably the best, most bizarre, example of estivation in an animal is the strange ability of the lungfish. Lungfish are a primitive type of fish that have lungs and can breathe air.
That comes in handy when the water runs out where they live. They burrow underground, secrete mucus to cover their bodies, which then hardens to seal in the moisture, all while breathing air. You might think this is a short, temporary fix to surviving a dried-up pond, but they can survive for three years like this.Earthworms also have some strange habits when it comes to estivation. When the soil starts to dry out, they ball up to try to conserve moisture. And not just any ball; they look like a fancy Boy Scout knot.
If the soil dries out further, they can encase themselves in mucus until it rains enough to come out of estivation.Other animals known to shut down to save energy through estivation are hedgehogs, snakes, crocodiles, snails and desert tortoises. Who would’ve thought that list of animals had anything in common!
So, let’s review. Estivation is one form of dormancy that some animals use to conserve energy under extreme hot and dry conditions. The metabolism slows, the heart rate slows, breathing slows and the animal usually seeks a cool place during estivation. In a more familiar form of dormancy called hibernation, the animal is usually trying to lower its energy needs in preparation for winter food shortages.
Torpor is a short, less than 24-hour, form of dormancy that lowers energy needs. Animals that estivate include lungfish (which estivate for up to three years), earthworms, hedgehogs, snakes, crocodiles, snails, and desert tortoises.