Image of a groundhog surrounded by flowers

Arctic ground squirrels live in the coldest parts of the world: the northern region of North America and Siberia in eastern Russia.

Matthias Breiter/Minden Pictures

STANDARDS

CCSS: 6.RP.A.3.C, MP2, MP6, MP7

TEKS: 6.5B

The Big Sleep

During the winter, some animals sleep for days on end to save energy and keep warm

Ingo Arndt/Minden Pictures

ZZzzz . . . The arctic ground squirrel can hibernate for up to 8 months!

When the weather turns cold, animals have to make a choice. Some migrate to warmer places to wait out the chilly months, while others grow thicker coats of fur to trap heat and stay warm. But another group of animals snooze until the spring in a state called hibernation.

Hibernation is a sleeplike state that animals enter to save energy in the winter, when there’s less food available and it’s harder to survive. When hibernating, an animal’s body temperature drops and its heart rate and breathing slow down. It also doesn’t eat or drink until it wakes in the spring. But not all animals hibernate for the same length of time or in the same way! See how three different animals prep for their winter-long rest.

When the weather turns cold, animals have a few options. Some travel to warmer places to wait out the chilly months. Others grow thicker coats of fur to keep them warm. But another group of animals snoozes straight through winter! This is called hibernation.

Hibernation is a sleeplike state. It helps animals save energy in winter, when there’s less food and it’s harder to survive. During hibernation, an animal’s body temperature drops. Its heart beats less often, and its breathing slows down. The animal usually doesn’t eat or drink until it wakes up in spring. But not all animals hibernate in the same way! Read on to learn how three different animals prepare for their long rest. 

Answer questions about how these animals wait out the winter. Round answers to the nearest whole number. Record your work and answers on our answer sheet.

Answer questions about how these animals wait out the winter. Round answers to the nearest whole number. Record your work and answers on our answer sheet.

mlorenzphotography/Getty Images (Bear); Lynn Rogers (Hibernating Bear)

ZZzzz . . . A black bear can hibernate for up to 7.5 months!

A. After stuffing themselves with nuts, berries, insects, and more, black bears hibernate through the winter. When a black bear wakes up in the spring, it weighs 260 pounds. It gains 33% of its starting body weight by the winter. How many pounds is that?

A. After stuffing themselves with nuts, berries, insects, and more, black bears hibernate through the winter. When a black bear wakes up in the spring, it weighs 260 pounds. It gains 33% of its starting body weight by the winter. How many pounds is that?

B.  What will the black bear’s new weight be after gaining that weight over the summer?

B.  What will the black bear’s new weight be after gaining that weight over the summer?

Michael S. Quinton/NatGeo Image Col./Minden Pictures (Frog); J.M. Storey/Carleton University (Hibernating Frog)

ZZzzz . . . A wood frog can freeze for up to 8 months!

Winter temperatures in the Arctic Circle drop lower than 3°F, so wood frogs freeze to survive! Ice forms in the spaces between the frogs’ cells. Luckily, they create a substance that keeps the ice from damaging their cells and tissues. About 64% of the water in a wood frog will freeze in the winter. If a frog’s body has 12 grams of water, how much of its water freezes?

Winter temperatures in the Arctic Circle drop lower than 3°F, so wood frogs freeze to survive! Ice forms in the spaces between the frogs’ cells. Luckily, they create a substance that keeps the ice from damaging their cells and tissues. About 64% of the water in a wood frog will freeze in the winter. If a frog’s body has 12 grams of water, how much of its water freezes?

De Agostini via Getty Images (Bat); Shutterstock.com (Hibernating Bat)

ZZzzz . . . A North American bat can stay in torpor for up to 1 month!

North American bats huddle together in caves to hibernate and avoid the chill. Instead of sleeping, the bats enter a state called torpor. They wake up every few days to refuel on insects, then go back to sleep. While in torpor, a bat’s heart rate is about 10 beats per minute. Its normal heart rate is about 300% of that. What is a bat’s normal heart rate?

North American bats huddle together in caves to hibernate and avoid the chill. Instead of sleeping, the bats enter a state called torpor. They wake up every few days to refuel on insects, then go back to sleep. While in torpor, a bat’s heart rate is about 10 beats per minute. Its normal heart rate is about 300% of that. What is a bat’s normal heart rate?

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