Sleeping animals: what’s the difference between hibernate, aestivate, dormant, lethargic, diurnal, nocturnal, and crepuscular?

Animals sleep. Some animals sleep at night, some animals sleep during the day, and some animals sleep in cold climates.

Animals that are diurnal are active mainly during the day and sleep at night.

Animals that are nocturnal are active mainly at night and sleep during the day.

Animals that are active mainly at dawn and dusk are crepuscular. They sleep during the day and during the night.

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Some animals hibernate. They go into hibernation for the winter, which means that they sleep and wake up when the weather becomes warm again. Animals will hibernate in a cave or tunnel so that they are not disturbed.

Many animals migrate for winter – they move to a location with warmer climate. They usually do this every year. Animals that cannot migrate during winter, may hibernate instead. They are resident (they stay home). Bears and skunks hibernate.

Some animals aestivate. Aestivation is animal dormancy, or sleep, similar to hibernation. Hibernation is winter sleep. Animals who aestivate can sleep for several years at a time. The lungfish aestivates during droughts when it is in the mud waiting for the riverbed to fill with water.

Other animals that do not migrate in winter, may become dormant. It is like hibernation, but they do not sleep for a long sustained period. When they are dormant, they are inactive. Snakes, for example, become inactive in cold weather. Alligators, crocodiles, and lizards become inactive in cold weather. They are all reptiles.

Reptiles are ectotherms, which means that their body temperature goes up or down depending on the temperature of the air. Ectotherms have a cooler body temperature at night when the air temperature is cooler, and a warmer body temperature during the day. Under the sun their bodies absorb heat and become warmer. In cold weather, they become dormant. To do this, they stop moving to conserve energy.

Dormant usually means that the animal is still and not moving. Lethargic means slow and inactive movements while the animals are awake – they are moving, but slowly.

Insects are ectotherms too. They are lethargic (slow and inactive) in cold temperatures. Often they will hibernate or become dormant in winter if they live in cold regions.

Some bee species migrate to another location in winter, and some bee species hibernate in winter, but most bee species are resident and stay in their hives, but become dormant (inactive) during winter. They are dormant because bees cannot fly if the air temperature is below about 17 Celsius (54 Fahrenheit).

Amphibians (frogs, toads, newts, salamanders, and axolotl) have fewer chambers in the heart than other animals. This enables amphibians to have a higher metabolic rate, which means that they can be very active for long periods of time instead of sleeping too much.

 

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Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM

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