When you think of an animal sleeping to escape the elements, you probably think of bears hibernating through frigid winter months. But there's a flip side, and it's called estivation, when animals "sleep" through scorching temperatures. Estivation helps animals survive by slowing their metabolism, which means they don't need to eat as much during hot months when vegetation and prey can be scarce. Some animals, like certain snails, estivate to prevent drying out by retreating back into their protective shells. Other animals, like the lungfish, will estivate underground, burrowing into the mud near water, where it remains dormant until the next wet season.

More mundane creatures also estivate. A 2013 study of common earthworms, for instance, found that the worms are capable of surviving in drought-ridden areas for weeks at a time thanks to estivation. That's good news for arid parts of the country, like eastern Colorado, which need earthworms to mix soils in dry, no-till areas of agricultural production.