Actually, we don’t need to worry about the frogs. They are well-equipped to deal with the cold weather, even with Arctic temperatures.

Frogs are ectothermic, which means that they rely on their environment to regulate their body temperature. Birds and mammals, including humans, are endotherms. We generate heat chemically and internally by breaking down food. The bodies of ectotherms reflect the air, ground, and water temperatures around them. One advantage that ectotherms have over mammals is that they can survive for long periods without eating.

In the fall, frogs first need to find a place to make their winter home, a living space called a hibernaculum that will protect them from weather extremes and from predators. The frog then “sleeps” away the winter by slowing down its metabolism. When spring arrives, it wakes up and leaves the hibernaculum, immediately ready for mating and eating.

Aquatic frogs and toads such as the leopard frog and American bullfrog usually hibernate underwater in streambeds or on pond bottoms. Because aquatic frogs need oxygen, they lie just above the mud, or only partially buried in the mud, so they are near the oxygen-rich water. They may even occasionally slowly swim around.

Terrestrial frogs and toads typically hibernate on land. Those frogs and toads that are good diggers like the American toads burrow deep into the soil, safely below the frost line. Other frogs, such as the wood frog and the spring peeper, aren’t good diggers and so must scout out their winter homes in deep cracks and crevices in logs or rocks, or they might dig down into the leaf litter.

These frozen peepers and wood frogs might look dead; their hearts have actually stopped beating. But the partially frozen frogs aren’t dead. Instead, they have a kind of natural anti-freeze in their bodies. Ice crystals form in their organs and body cavity, but a high concentration of glucose in the frogs’ vital organs prevents freezing. When spring approaches and its hibernaculum warms up above freezing, a frog’s frozen body will thaw, and it will come back to life.

As you go about preparing for winter, think of the frogs with their amazing adaptations for survival, safe in their winter homes, waiting for spring.

Here’s a video from YouTube about the hibernation of a wood frog. It’s pretty amazing—take a look!

This is a partial repost of an earlier post from December 2010. Most of the information from the post came from an article in Scientific American, How Do Frogs Survive the Winter? by Rick Emmer.

It’s back-to-school time again, a time when teachers may be planning their life science classes. What better way to illustrate an animal’s life cycle than by teaching kids about the remarkable transformation of a tadpole into a frog?  Unfortunately teachers may decide to use grow-a-frog kits to teach children about metamorphosis.

I have to admit I have mixed feelings about advising teachers not to raise live amphibians in the classroom. As a child, my love of animals was fostered by the various animals I kept at home, including fish and turtles. I probably would have enjoyed having a live frog in the classroom.

But the authors of an article in the Herpetological Review, “Considerations and Recommendations for Raising Live Amphibians in Classrooms,” remind us that the world is no longer a simple place: innocent acts like catching tadpoles and releasing them later into local ponds are much more complicated than they used to be.

Releasing live  frogs “grown” in the classroom into the wild can potentially harm native amphibians (even if the animals are native to the area) by possibly spreading infectious diseases, such as the deadly chytrid fungus, a disease that has wiped out entire frog populations. It may also introduce species (such as bullfrogs) that might become invasive and disrupt local amphibians.

After we wrote a few posts discouraging people from buying the Frog-o-Sphere kits, quite a few readers who owned the kits were distressed and emailed us, asking  if they should “let the frogs go.” We wrote back immediately, telling them not to release the frogs into the wild. Instead we referred them to frog care sites and books. If you’ve already purchased a frog kit, it is your responsibility to take care of the frog. Releasing it into the wild helps neither the frog nor the environment.

The problems with the classroom grow-a-frog kits are similar. After the tadpole grows into a frog, the children may become bored with it and the teacher may decide to release it into a local pond. Or at the end of the school year, the teacher may give it to a family, who then releases it somewhere in the neighborhood.  As advised in the article above: “This should never be done, and in fact, it is illegal in several states. No amphibian purchased or received from any commercial or informal (e.g., a neighbor) source may be released into the wild. This recommendation applies whether the species is technically ‘native’ to the region of release, or not.”

If you decide to purchase a grow-a-frog kit (which we hope you don’t), you will be making a commitment to take care of the frog for its natural lifespan.

How can teachers and parents teach children about the life cycle of frogs without raising live frogs? We would suggest contacting a local nature center and setting up a field trip in the spring, where the children can see eggs and tadpoles in the wild.  This past spring while hiking I frequently saw frog egg clusters in ponds and swamps, and it’s fairly easy to see tadpoles as well. A local naturalist will know where to look.

To prepare the children for what they might see in the spring, here are some resources:

The Amphibian Project : Classroom curricula, field projects and hands-on activities, fundraising ideas for students, and links.

Amphibians. 35 min. (Eyewitness DVD) Describes amphibian life cycle and anatomy; behaviors and adaptations; and amphibian characteristics. Grades 5-12

Two frog life cycle plastic sets: