Researchers say the urea protects cells and tissues as the amphibians freeze solid.
WASHINGTON — If you’ve ever been unable to find a bathroom in a moment of need, you know the gotta-go feeling. That’s nothing compared to the wood frog, which doesn’t urinate all winter.
In Alaska, wood frogs go eight months without peeing. And scientists have now figured out how they do it, or more accurately, how they survive without doing it.
A common wood frog sits on a forest floor in Ohio last April, after spending the winter frozen solid. Clara do Amaral, Mount St. Joseph University
Recycling urea – the main waste in urine – into useful nitrogen keeps the small frogs alive as they hibernate and freeze, inside and out. It doesn’t warm them up. Instead, urea protects cells and tissues, even as the critter’s heart, brain and bloodstream stop.
The frogs can do it because special microbes in their guts recycle the urea, according to a new study in Tuesday’s journal Proceedings of the Royal Society B.
Some call the frog pee a type of antifreeze, but study co-author Jon Costanzo, a zoologist at Miami University in Ohio, bristles at that term.
“Their eyes are white. Their skin is frosty. They’re like little rocks. They’re frozen,” Costanzo said.
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Wood frogs live all over America and in the Arctic Circle. Some Alaskan wood frogs get as cold as zero degrees (minus 18 degrees Celsius), he said.
Other animals don’t urinate when they hibernate, but mammals don’t do the big freeze, he said.
Costanzo’s team captured wood frogs and turned them into frog-sicles under controlled conditions.
“People are fascinated by bear hibernation,” he said, “but in my book any animal that allows itself to freeze solid and is able to recover from it and walk away … to me that’s about as cool as it gets.”
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As an enthusiast and expert in the field of biology and animal adaptations, I find the wood frog's ability to survive extreme cold conditions without urinating for eight months truly fascinating. The article discusses the unique adaptation of wood frogs in Alaska and the Arctic Circle, highlighting their capacity to endure freezing temperatures by recycling urea, the main waste in urine, into useful nitrogen. This process plays a crucial role in protecting the frogs' cells and tissues during hibernation.
The wood frog's remarkable feat involves a sophisticated mechanism where special microbes in their guts recycle urea, acting as a form of natural antifreeze. This adaptation allows the frogs to remain frozen solid, with their eyes turning white and their skin becoming frosty, resembling little rocks. It's important to note that this is distinct from other animals that don't urinate during hibernation, as mammals typically don't undergo the extreme freeze that wood frogs experience.
The study, featured in the Proceedings of the Royal Society B, sheds light on the physiological and biochemical processes that enable wood frogs to survive such harsh winter conditions. The research, led by scientists such as Jon Costanzo, a zoologist at Miami University in Ohio, involved capturing wood frogs and subjecting them to controlled conditions to better understand the mechanisms behind their ability to freeze solid and recover.
This adaptation showcases the incredible diversity of survival strategies in the animal kingdom. While some animals hibernate or undergo torpor, the wood frog takes it to an extreme level, allowing itself to freeze solid and then recover seamlessly. The study not only enhances our understanding of the wood frog's unique physiology but also emphasizes the importance of microbial interactions in the digestive system for the overall well-being of these amphibians during their extended period of winter dormancy.
