Animals That Survive Freezing, Drought, or Long Hibernation

On the forest floor, a wood frog can survive part of its body water turning to ice. Its heartbeat and breathing stop while it is frozen, then resume as it thaws. Compare it with the Arctic ground squirrel, which can drop below the freezing point without forming ice in its body.

An Arctic ground squirrel spends much of the year in an underground burrow. During hibernation its body temperature can dip below the freezing point of water while its tissues stay unfrozen. It periodically warms up again. Taken together, those changes make its winter different from a long stretch of ordinary sleep.

A hazel dormouse spends much of the active season in shrubs and trees, then usually hibernates in a nest close to the ground. Look for the shift in shelter. The place it chooses for winter gives it different conditions from the branches where it forages in warmer months.

During cold weather, when flying insects can be scarce, a common poorwill can enter torpor. Its body cools and it uses less energy than it does while active. The bouts can last much longer than a night, giving this North American nightjar a way to get through periods when hunting is poor.

Painted turtle hatchlings sometimes spend their first winter in the nest. They can supercool, staying unfrozen even when their temperature dips below freezing. The soil around the nest affects how well that works. Hatchlings can also survive limited freezing.

Some tardigrades in moss or other damp surroundings can survive when their surroundings dry out. The animal contracts into a compact form called a tun and becomes inactive. It can become active again when water returns. The picture shows an active tardigrade with its legs extended.

A brine shrimp can get through a dry spell before it hatches. Its embryos can remain dormant inside protective cysts. The adults in the picture show the swimming stage that follows once development resumes.

When water recedes, a West African lungfish can wait in a cocoon in the mud. It breathes air and reduces its activity until the water returns. Compare it with the spadefoot. Both spend dry periods underground, but one is a fish waiting for its pool to refill.

Couch’s spadefoot stays underground through much of the dry season. After heavy rain it can emerge to breed in short-lived pools. The pause and the sudden activity belong to the same desert life cycle, with the wet weeks offering opportunities that the dry months cannot.

In hot, dry conditions, a brown garden snail can retreat into its shell and close the opening with a temporary membrane. The barrier helps limit water loss until conditions are better for movement and feeding. This is a dry-weather pause you may see close to home.

This grassland squirrel retreats underground for winter and relies on stored body fat. Its heart rate and body temperature fall during torpor, then rise during brief waking bouts. Look at the stripes in the photograph before comparing its winter habits with those of the less striped Arctic ground squirrel.

Some of these tiny animals live in places where a film of water regularly disappears. They can contract as they dry and become active again when water returns. The ability varies across species. If you compare them with tardigrades, the shared feature is the pause during drying rather than the way the animals look.