Wood Frogs – The Lone Alaska Amphibian
By: Courtney Dowd-Stanley
Have you ever heard of the lone Alaska amphibian that freezes itself alive every winter? The one and only wood frog is the lone amphibian able to live as far north as Denali in Alaska’s interior region. The fascinating camouflage coloring of the wood frog makes them hard to spot, but when the rare sighting does happen, pay respect to these tiny creatures as they are wildly impressive and so very resilient.
One of the most remarkable things about wood frogs is their ability to live, and thrive, in subarctic areas with incredibly harsh weather for more than half of the calendar year. The extreme environment of Alaska’s interior region means that there are very few species of amphibians that will ever be able to live here.
Generally wood frogs are found in forests and wetlands. They are pretty darn small, averaging only one to seven centimeters long. They breed in seasonal ponds during the late-spring and early summer, after coming out of “hibernation” where they essentially freeze solid all winter.
Research states that scientists speculate “wood frogs were able to adapt to the harsh environment in interior Alaska because they change so quickly from tadpole to frog before the water begins to freeze in the fall.” Frogs are ectotherms, which means that their body temps fluctuate with their surroundings as well as with the ambient air temperatures of their environment. But when was the last time you heard a frog croaking in the dead of the winter? Answer: Never. The calm of Alaska’s winter offers no such noise. So how do you reckon they survive and thrive? Well, the answer will fascinate you!
Wood frogs use chemicals called “cryoprotectant” to survive freezing temps through Alaska’s late-fall, winter, and spring seasons. In the fall, wood frogs will usually prepare for their “winter hibernation” by burrowing into decaying leaves on forest floors. When the temperature drops below 32° Fahrenheit, the eyeballs and extremities of the body will begin freezing on a daily basis. When the freeze first starts happening, the wood frog’s brain is stimulated to send a message to it’s liver, which then starts to convert stored glycogen into glucose (“sugar”). Then, the glucose circulates in the wood frogs bloodstream and into the cells where it then lowers the freezing point of water. Essentially, this protects the cells from damage and cuts down on their potential of a harmful dehydration experience. As the weather gets even colder, wood frogs eventually freeze solid throughout the entire winter.
What is the most intriguing is that these hibernating wood frogs are inanimate, meaning they don’t breath and their hearts don’t beat at all for the whole winter season. Science has proven that the core organs of a wood frog freeze last and thaw first, such as the heart and liver. Circulation and metabolism are maintained during hibernation for the longest period of time.
How do Alaskans in the interior know when spring has arrived?! The surprisingly loud calls of wood frogs will blow your mind! Check out the YouTube video below for an awesome listen.
Looking for another great read? Check out these 10 Undeniable Reasons Denali ‘The Great One’ Is Alaska’s Top Attraction. Or, 7 Road Trips That’ll Fuel Your Wanderlust To Travel Alaska This Summer. Don’t miss these 10 Ridiculously Rare Alaska Attractions That You’ll Be Blown Away By. You might also enjoy, Alaska’s Unreal Upside-Down Forest at Glacier Gardens in Juneau, Alaska.