Scientists Say: Torpor | Science News for Students

Scientists Say: Torpor

This state is more than just a deep sleep
Feb 6, 2017 — 6:50 am EST

Hummingbirds are one of the few bird species that go into torpor at night. This lets them conserve energy when food is scarce and temperatures are cool.


Torpor (noun, “TORE-purr”)

This is a condition of decreased body temperature and low energy use in an animal. An animal that is in torpor is not asleep. It’s torpid. When an animal sleeps, its body temperature and the energy its body uses remain relatively high. But when an animal enters torpor, these plummet. Torpid animals can have extremely low body temperatures and use very little energy. It’s a good way for an animal to survive a time when food may be scarce.

Torpor doesn’t have to last a long time. Some birds, rodents and bats do it daily. Other mammals go into long-term torpor for days, weeks or months.

In a sentence

Hibernation is a kind of long-term torpor.

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Power Words

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bat     A type of winged mammal comprising more than 1,100 separate species — or one in every four known species of mammal.

birds     Warm-blooded animals with wings that first showed up during the time of the dinosaurs. Birds are jacketed in feathers and produce young from the eggs they deposit in some sort of nest. Most birds fly, but throughout history there have been the occasional species that don’t.

hibernation     A state of inactivity that some animals enter to save energy at certain times of year. Bears and bats, for example, may hibernate through the winter. During this time, the animal does not move very much, and the use of energy by its body slows down. This eliminates the need to feed for months at a time.

mammal     A warm-blooded animal distinguished by the possession of hair or fur, the secretion of milk by females for feeding the young, and (typically) the bearing of live young.

rodent     A mammal of the order Rodentia, a group that includes mice, rats, squirrels, guinea pigs, hamsters and porcupines.

torpor   A state of decreased activity in an animal. During torpor, an animal’s body temperature decreases and its cellular activity slows down.