What Adaptations Does a Wood Frog Have That Enable It to Survive in Deciduous Forests?
NPS Photo
Freezing Solid
The nigh remarkable thing most wood frogs happens not in the summer when they transform from tadpoles to frogs, but in the winter when they hide.
The northern forests of Alaska and Canada have some of the most dramatic temperature ranges in the world. Summer days stretch to 24 hours and temperatures tin can climb into the 90's. Winter brings some of the globe's coldest temperatures: it is non unusual to have temperatures of minus 50 degrees Fahrenheit. Prospect Creek, just s of the Brooks Range, had the coldest temperature ever recorded in Alaska—minus 80 degrees Fahrenheit. Nigh certainly, in that location were hibernating forest frogs near Prospect Creek when that record was gear up.
This is the winter globe in which the wood frog must survive. Think, frogs are cold blooded, so their body temperature is about the aforementioned as the surrounding air. How do these delicate fiddling creatures endure the intense, protracted, iron-cold subarctic wintertime?
This mystery has intrigued scientists for a long time. Biologists have studied wood frog hibernation and what they've learned is truly amazing.
Nigh frogs survive northern winters past hibernating deep under water, in ponds, lakes and streams—they are cold and dormant but their trunk temperature never falls below freezing.
Wood frogs accept a different strategy. They hide by nestling down into the leafy litter on the forest flooring. The leaves, duff and overlying snowfall give some insulation from extreme cold, merely the frogs are not protected from subfreezing temperatures as they would be if they chose the underwater strategy.
Evelyn Davidson
Researchers accept establish that woods frogs spend the wintertime frozen! This astonishing strategy allows forest frogs to become active very early on in bound, considering the land thaws and warms more than speedily than the water ice-covered lakes The newly agile frogs can mate and lay eggs in small ponds and even in melt water pools that dry out up by midsummer. Past contrast, frogs that hide underwater accept longer to become agile, so they must breed later. These frogs need permanent water that won't dry out.
For about other animals, survival depends on protecting themselves from whatsoever condition that could freeze their flesh. Why is freezing so unsafe? Several things can happen: If ice crystals form inside an beast they can puncture blood vessels. When claret freezes, there is no mechanism to deliver oxygen and nutrients to organs, so extreme metabolic damage occurs. And ice severely injures cells by drawing out water and causing dehydration, scrambling the interior structure of cells and fracturing the cell walls. The event is pervasive and mortiferous internal damage.
Richard Nelson
Withal wood frogs have evolved means to freeze solid for upwards to 8 months each twelvemonth. They've accomplished what would seem to be a biological phenomenon. How practise they pull this off?
At the beginning of wintertime, ice chop-chop fills the wood frog's abdominal cavity and encases the internal organs. Ice crystals form betwixt layers of skin and muscle. The eyes turn white because the lens freezes.
At the aforementioned time, the wood frog'due south liver produces big amounts of glucose that flushes into every cell in its body. This syrupy sugar solution prevents the cells from freezing and binds the water molecules inside the cells to prevent dehydration.
So on the i hand, the forest frog's torso allows ice to class effectually the outsides of cells and organs; and on the other hand, information technology prevents water ice from forming inside the cells--thus fugitive the lethal damage suffered by most animals when they freeze.
What does a hibernating forest frog look similar? There is no musculus movement. No heartbeat. No breathing. For the unabridged winter, the wood frog is like a lump of hard, frigid, icy rock carved in the shape of a frog. Simply information technology's alive, in a land of suspended animation.
In leap, the wood frog thaws from the inside outward. Showtime the heart starts chirapsia. And so the brain activates. Finally, the legs move.
Nobody yet understands what starts the wood frog's middle after being frozen and inert for the entire northern wintertime. Once the frog is fully thawed, information technology heads off through the woods to find a convenance pond or other suitable h2o.
The wood frog is completely undamaged past conditions that would exist fatal to nearly all other animals.
Woods Frogs and Humans
Glucose in the wood frog'southward blood keeps it from freezing during the extreme arctic winter temperatures. This is the same as the blood sugar in all vertebrate animals, including humans.
Hibernating wood frogs tin can tolerate blood carbohydrate levels 100 times higher than normal without the damage suffered past human diabetics when their blood sugar is only 2 to 10 times above normal. Understanding how frogs tin do this might provide valuable knowledge to help in the management of high blood carbohydrate in people with diabetes.
Also, the wood frog's ability to withstand freezing may help researchers discover how human organs used for transplants could be frozen and thawed without harm. This would increment the allowable time between removing an organ from a donor and implanting it within the recipient, which could make many more transplants possible.
Researchers are also interested in how the wood frog's body can stop blood circulation and showtime information technology again many months later without claret clots or other injuries. Understanding the mechanism which allows this could be valuable for treating people after their blood menses is temporarily halted by eye attack or stroke.
Source: https://www.nps.gov/gaar/learn/nature/wood-frog-page-2.htm
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