A year ago, I wrote an article about frogs that have adapted to survive being frozen. Turns out these frogs are not the only creatures that have developed ways to survive extreme cold. One of my favorite cold tolerant species is the Gynaephora groenlandica (no, I can’t pronounce it either!). It’s also known as the Arctic woolly bear moth. Now I realize that most of us don’t have these creatures in our backyards, but their ability to survive harsh winters make them a fun topic to explore with kids this time of year.
Arctic woolly bear moths spend the majority of their lives in caterpillar form—fuzzy, golden-and-orange little guys about 2 inches long. In order to pupate (form a cocoon), they must reach a certain body mass. However, the short Arctic summers don’t allow them to eat enough in one season to reach this magic number.
The caterpillars solve this problem by overwintering in their larval form. Specific adaptations in their bodies, including the ability to produce antifreeze compounds in their cells, allow them to survive temperatures down to -90 degrees F. Each summer they emerge for to eat and eat and eat before spinning a hibernaculum (silk “sleeping bag”) that will house them until the following summer.
Artic woolly bear caterpillars actually spend the majority of their lives frozen! After around seven summers (and up to 14!), they build up enough food resources to pupate into an adult moth. The adult moths have a few frantic days to mate and produce the next wave of super trooper caterpillars. Then the whole cycle starts all over again!
- Frozen Planet from Discovery had a segment on the Arctic Woolly Bear Caterpillars. You’ll find it here.
- My article on Antifreeze Animals (wood frogs) appeared last year on the KIDS DISCOVER Teacher’s Blog. It includes a classroom activity that examines one mechanism (cryoprotectants) that these animals use to survive being frozen.
- A woolly bear caterpillar craft from Samantha at Stir the Wonder–you can change the colors to match the Arctic woolly bear.