Over the course of around half a day, the frogs take their time coming back to life before they’re ready to hop on over to their local pond and kick off the breeding season. They start to breathe again, Barnes said, and then their hearts start to beat. Months later, when the spring sun melts the ice and signals that it’s time to wake up, the wood frogs slowly begin to thaw. “Until morning it doesn’t thaw, and then they’re good to go.” “They’re building up glucose levels in their tissues like a stair step - higher and higher and higher levels,” he said. The sugary cryoprotectant builds up inside them the whole time, Barnes said, adding that a new glucose production event is triggered each time ice touches their skin. During the day, the frogs thaw alongside their leafy homes. Over that time period, the wood frogs engage in a cycle of freezing and thawing.ĭuring the cold night, the glucose flows into their bloodstream, tissues and cells. It can take a week or so for the frogs’ new shelter to completely freeze for the rest of the winter. He noted that they produce that glucose using a supply of glycogen that’s stored in their livers.īut this process doesn’t happen overnight. “It’s glucose - blood sugar - that acts as a cryoprotectant, and they become extremely, extremely sweet as they freeze,” Barnes said. Video credit: Roger Topp/University of Alaska Museum of the North Don Larson/University of Alaska Fairbanks Department of Biology and Wildlife Brian Barnes/University of Alaska Fairbanks Institute of Arctic Biology. This sped-up video illustrates the freezing and thawing process for hibernating wood frogs. Making sure ice doesn’t form in their cells is a top priority. When they find a spot that suits them, Barnes said, these frogs spin to the left, then spin to the right, and repeat that process until they’ve sunk down about 2 or 3 inches and are all covered up.Īs the cold sets in, frost creeps across the leaves and reaches the immobile frogs, who then begin the process of releasing a cryoprotectant that keeps their bodies from drying out as they freeze. Plant matter like leaves and moss on the ground serve as their shelter for the cold months ahead. When autumn comes to a close, adult wood frogs hunker down fairly close to the shores of ponds where they plan to breed the following spring. This species is found across a large swath of North America, from where Canada meets the Arctic Ocean through parts of the Appalachian Mountains. The wood frog has an impressive geographic range. If you got up this morning and - like a certain groundhog - saw your shadow, or are thinking “sign me up for a weekslong nap,” perhaps you won’t be surprised that there are ways that humans eventually might use these strategies to our advantage. That scenario may create more problems for some species as climate change fuels more unpredictable weather patterns. READ MORE: Punxsutawney Phil predicts 6 more weeks of winter on Groundhog’s Dayīut tragedy can strike if an animal miscalculates where it chooses to hibernate, or if there’s a mismatch between when its internal clock tells it to venture back into the world and the on-the-ground conditions that greet it. When the temperature warms, they emerge from their dormant state and pick up where they left off. Instead, they enter an in-between state that can resemble a kind of living death. With those bodily processes no longer fully in action, in most cases they don’t need to take in any nutrients, nor do they excrete any waste. (But hibernating isn’t exclusive to cold climates - there’s a lemur in Madagascar that does it, too.)Īnimals enter hibernation by slowing down their metabolic rates to a near - or, in some cases, complete - standstill. Barnes, professor of zoophysiology in the Institute of Arctic Biology at the University of Alaska Fairbanks. The term “hibernation” is derived from Latin, and it refers to “spending the winter in a lethargic state,” said Brian M. But a subset of creatures who tough it out are equipped with a biological game-changer: the ability to hibernate. Some of us migrate in search of brighter skies until spring rolls around. The sun is low, temperatures flirt with freezing (or worse) and fresh food is scarce. Maybe you can relate: Winter isn’t always the ideal time to be an animal.
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