When winter arrives, it’s common for humans to stay indoors and protect themselves from the cold. But what about the animals? Can they survive in freezing temperatures?
Some animals choose to hibernate during the winter. For example, bears find a warm place and sleep for several months. Other animals, like birds, migrate to warmer areas. However, not all animals can migrate or hibernate.
Take frogs, for instance. They don’t have thick fur or skin like bears, and they can’t fly to warmer places. Yet, some frogs, such as the wood frog, live in various parts of the United States, including Alaska and above the Arctic Circle. How do these small creatures survive in such cold areas?
Scientists have recently studied wood frogs and made some fascinating discoveries about them. So, what happens to wood frogs when the temperature drops below freezing? They freeze!
As the air gets colder in September, wood frogs in the woods hide under layers of leaves and other ground cover. Something incredible happens then: they stop breathing, their hearts stop beating, and their blood stops flowing. Eventually, they freeze.
Approximately two-thirds of the water in their bodies turns into ice. They appear lifeless to the naked eye. They don’t move, and if you try to bend their arms, they will break. However, life still exists deep inside them.
To study wood frogs in freezing environments, scientists attached tiny radio transmitters to a group of frogs. These transmitters allowed scientists to track their movements and study them while they were frozen during the winter.
After two years of study, none of the frogs died. Scientists discovered that the frogs could survive temperatures as low as 0º F for up to seven months. This finding surprised scientists, who previously believed that these frogs could only survive for a few weeks in warmer temperatures.
Scientists found that the water inside individual cells does not freeze, but the water between cells freezes completely. Although cells still function, they cannot communicate with each other.
Wood frogs have special proteins in their blood that cause the water in their blood to freeze first. As ice draws water out of nearby cells, the cells begin to shrink. This process could be fatal if it wasn’t for a substance that acts like antifreeze within the cells.
Scientists believe that early freeze/thaw cycles help wood frogs convert the glycogen stored in their livers into glucose in their cells. They think that high levels of glucose inside the cells allow wood frogs to survive being frozen for such a long time, as the glucose keeps enough water inside the cells to keep them alive.
Amazingly, when spring arrives and temperatures rise, frozen wood frogs slowly thaw out. Their hearts start beating, their blood starts flowing, and they begin to breathe again. Glucose is converted back to glycogen, and they can eventually hop away to the nearest pond or lake to begin the mating process.
Give It a Try
Aren’t frozen frogs fascinating? Keep exploring with a friend or family member by trying out the following activities:
Are you ready to embark on an outdoor adventure? If so, grab a friend or family member and join forces to find a frog! To locate these amphibians, you may need to explore a local park or forest area. Take pleasure in strolling through the beautiful outdoors. In case you’re having trouble finding a frog, try thinking like one. Consider their preferred food, habitat, and proximity to water. Let these insights guide your search. Good luck! Once you spot a frog, capture some pictures and observe it in its natural surroundings. Take note of its behavior, movements, and reaction to your presence.
Have you ever encountered a frog in the wild? If so, were you able to identify its species? Frogs come in various types. Next time you encounter one in its natural habitat, utilize an online resource to help with identification. For instance, visit the Discover Life website to learn more about the diverse frog species you might come across. Considering your location, which types of frogs are most likely to inhabit your area?
The Wood Frog Interview
Up for a challenge? How about conducting an interview with a wood frog? No, you don’t have to magically speak frog language or encounter a talking frog. Instead, unleash your imagination and compose a set of questions and answers that explore what it would be like to converse with a wood frog about its life. What is the experience of freezing and then thawing? Is it painful? Are you aware of your surroundings during this process? These are just a few examples of the questions you can ask. Get creative and share your imaginative interview with a friend or family member!