Their Blood Runs With Antifreeze

Here in mid-autumn, most of State Park’s summer resident birds and some insects have flown off to warmer climates, but many other animals remain through the winter. Some of the year-round residents are either scurrying around looking for extra food to help to get them through the winter while others are looking for a safe place to sleep away the winter, protected from the cold and snow.

For a handful of animals in the park, finding a place away from the cold and snow can be a challenge due to their inability to dig deep into the ground to escape the cold. Instead, they burrow under the leaves, rocks, rotting logs, or tree bark to escape the worst that winter offers. So a few animals like wood frogs, common box turtles, red efts, and mourning cloak butterflies have a different strategy – the ability to tolerate freezing!

These close to the surface locations protect the animals from snow, ice, wind but not cold winter temperatures. When the temperature in the hibernation spot drops below 32o F, these hibernators freeze, solid.

jm-storey-carleton-university
Frozen wood frog in Ken Story’s Lab, Carleton University, photo by JM Storey , Carleton University

And there they can remain until the warming days of spring when they thaw, have a snack, and head off to breed.

Some of the animals that tolerate freezing include:

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How are they able to freeze solid then defrost and still be alive?  Natural chemicals and processes in the animal’s blood prevent them from freezing.  The animal’s body produces an “anti-freeze” as the temperature begins to drop; the animal’s body concentrates sugars and other compounds that prevents the animal’s organs from freezing.  The antifreeze prevents the animal’s organs from freezing.  A frozen animal will stop breathing and the heart will stop beating. Most of the fluid in the blood pools in the animal’s body cavity.

In spring, as the weather warms, the animal starts to defrost, and its lungs and heart resume working.  They defrost from the inside out, with the legs and feet being the last to defrost.

Surviving by freezing is just one of the amazing adaptations animals have developed to survive northern winters.

Resources

Cold-blooded in the cold: hibernation Conservationist for Kids, NYS Dept. Conservationist

Emmer, Rick. How do frogs survive winter? Why don’t  they freeze to death? Scientific American

Ken Storey Lab

Rosen, Meghan. Natural antifreeze prevents frogsicles, Science News

Videos

NOVA scienceNOW (2012, July 23). Frozen Frogs.

Smithsonian Channel. (2015, June 18). Frogsicles: Frozen But Still Alive.

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