Why do frogs hibernate

During the winter, low temperatures make it very difficult to be active and food shortages further contribute to this problem. The best strategy to handle the problem is to hibernate and live off of stored fat. The rate of metabolism is very reduced so not a lot of energy is required. When temperatures approach freezing, most species of frogs seek protection below the freeze line.

Some species jump into the water and prepare to hibernate at the bottom of ponds or under the banks of streams. Because water is a good insulator and retains heat better than other environments, it is a good place to wait out the winter. An active frog breathes oxygen from the air. At least its nostrils are above water above photo and the throat area can be seen moving as it pumps air into the lungs.

There was no frog sex that produced tadpoles that grew into frogs. The belief, until just a few hundred years ago, was that frogs died when the cold weather came and in the spring mud spontaneously turned itself into frogs.

It seemed implausible that frogs survive winter. As far as folks could see in those days, frogs disappeared in the winter and then popped out of the mud when spring came. So the frogs themselves must be made of mud. It was the clearest and most logical answer to why frogs came out of the mud every year. Photo by Lisa Brown.

Frogs do hibernate. Crucial thing is to be on top of the mud and not buried in it. Being on top of the mud lets oxygen from the surrounding water get in through their skin.

The rest of their body systems slow right down and they wait out the winter. This slowing of body systems during hibernation is a bit like other kinds of hibernation we know about in mammals such as bears, bats, and ground squirrels.

But of course frogs are amphibians and so their hibernation is very different in some ways. Being amphibians they are cold-blooded, or ectothermic. They have to take heat from their surroundings. Some other ectothermic animals, like snakes or crocodiles, sit still in the sun to keep warm. Frogs can be found hanging out on the bottom, sometimes even slowly swimming or moving around.

Frogs and toads that spend most of their time on land can usually burrow down below the frost line in burrows or cavities called hibernacula, or hibernating space. Some frogs, including various species of tree frogs, like spring peepers Hyla crucifer , are not very good at burrowing. They go as deep as they can or squeeze into cavities, crevices and logs. In this case, sometimes the frog will actually freeze solid! The danger in freezing is the formation of ice crystals that puncture cells and organs.

But these frogs have high concentrations of glucose, or sugar, which is a natural antifreeze. Amazingly enough, their hearts actually stop beating. Despite their fragile appearance and inoffensive ways, they have countless strategies to deal with the most severe climates this planet has to offer. They can be found at the Arctic Circle, in deserts, in tropical rain forests and practically everywhere in between. Some of their survival strategies are nothing short of ingenious. Various frog species use two strategies to deal with environmental extremes: hibernation and estivation.

Hibernation is a common response to the cold winter of temperate climates. After an animal finds or makes a living space hibernaculum that protects it from winter weather and predators, the animal's metabolism slows dramatically, so it can "sleep away" the winter by utilizing its body's energy stores. When spring weather arrives, the animal "wakes up" and leaves its hibernaculum to get on with the business of feeding and breeding. Aquatic frogs such as the leopard frog Rana pipiens and American bullfrog Rana catesbeiana typically hibernate underwater.

A common misconception is that they spend the winter the way aquatic turtles do, dug into the mud at the bottom of a pond or stream. In fact, hibernating frogs would suffocate if they dug into the mud for an extended period of time. A hibernating turtle's metabolism slows down so drastically that it can get by on the mud's meager oxygen supply.