Somewhere, not too far from the cozy warm house where I sit and write this, an Arctic Woolly Bear Caterpillar (Gynaephora groenlandica) sits frozen solid, in the spot where the dropping temperatures of an Arctic fall found it. It is one of the most cold tolerant species of insects known. It is also long lived. The caterpillar lives for fourteen years before becoming an adult. Fourteen years of freezing solid and thawing again, alive.
It is hard for most people to comprehend this fact, our minds won’t let us accept (with the possible exception of Walt Disney and other cryonics believers) that a living creature can be frozen solid, for periods of 9 or so months, and still survive. The reasons this remarkable insect is able to survive living in the high arctic are many and complex. It’s tissues are freezing tolerant partially because of the presence of natural antifreeze, such as glycerol and others. During its active summer phase it warms it’s body, often to several degrees above the ambient temperatures by actively basking in the sun, and orienting it’s body to maximize the effects of basking.
The caterpillar thaws in the spring when it’s body temperature approaches -8 degrees C. Although it has thawed, at that point it still isn’t active, and it is in a kind of suspended animation until it warms further. At a few degrees above zero it finally becomes active, and is able to feed at temperatures in the mid teens. It has very little time in the short arctic summers, even with active warming strategies, to feed and grow, so it is perhaps not surprising that it takes 14 years to work its way through its instars to adult hood.
With all of the time it spends frozen, it probably seems like quite a short life to adulthood, and it of course has no way of knowing just how remarkable and wonderful it truly is.
Comments
3 responses
amazing life history Clare, what a remarkable insect.
Wow, how, um, cool!
i had a frozen cabbage in my fridge when i got it out i found a frozen caterpillar which had layed lots of eggs and was in the middle of laying one. i thought it was dead, so i left it but within half hour it had moved. half hour later it was stretching up, had layed its egg and seemed very inquisitive. I must say im amazed by the little creatures now!