Kate Furby: Some caterpillars have evolved with antifreeze in their body cavities and can become caterpillar popsicles to survive the cold winter. But climate change could threaten it.
Martha Weiss: So there are caterpillars that have been reported that can be placed in ice cubes, frozen, and when the ice cubes melt, they can stand up and walk away.
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Furby: You may have seen them scooping up fallen leaves in the fall. They are shaggy and curly and are noted for their rumored weather forecasting skills. I’m talking about the Woolly Bear Caterpillar, or Isabella Tiger Moth.
These little creatures have orange waistband stripes, the width of which is rumored to predict the length of winter. teeth What is scientifically amazing is how caterpillars survive the winter.
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I’m Kate Furby. science, quick.
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Furby: Unlike humans and other mammals, caterpillars cannot regulate their body temperature. And unless they are burrowed or cocooned, they are exposed to the elements. Woolly caterpillars, like their name, are covered with spiky fluff.
Weiss: I’m sure these furs, which you might think of as the little down jackets that caterpillars wear, provide a bit of insulation.
Furby: Dr. Martha Weiss, a biologist and professor at Georgetown University who studies plant-insect interactions. She says the spiky little caterpillar jacket has a particular use, but not as much as you might think.
Weiss: These hairs are thought to have evolved as a way for caterpillars to protect themselves from predators.
Furby: Hmm, it’s actually a super-strong little jacket. But here’s the caterpillar’s dilemma.
Weiss: The important thing is to get very cold. And they have a lot of water and can freeze.
Furby: And while the famous fur jackets offer protection, they don’t provide the woolly bear caterpillar-like insulation needed in harsh Chicago winters. What they do is a little more biochemical. .
Weiss: As much as caterpillars can be said to have sleeves, they have more biochemical tricks in their sleeves.
Furby: Wow they must have 16 little sleeves! But okay, what are their options for survival?
Weiss: They can also do biochemical and physiological things to make them less likely to turn into ice cubes. They basically make a glycerol-like compound that they put into their cells.
Furby: For those unfamiliar with glycerol, it is a naturally occurring alcohol compound. It works in a similar way to salting the sidewalks in the city to keep them from freezing. The compound in the caterpillar’s body lowers the freezing point and buys it time. And they do even more amazing things.
Weiss: They move water out of the cell so that it freezes in the extracellular space.
Furby: that is…
Weiss: Of course, when water turns into ice, it gets bigger. When the cells fill with water and freeze, the cell membranes can rupture and harm the caterpillar. is.
Furby: So these little guys can freeze hard all winter and then thaw in the spring to get up and go away.
Weiss: They can actually freeze and thaw many times over the winter.
Furby: But falling asleep and waking up again comes at an energetic cost.
Weiss: Studies on Isabella tiger moths show they can actually go through a few freeze-thaw cycles, but that’s not really great for them. It’s better
Furby: not only that…
Weiss: I believe there is also damage that occurs to some of the caterpillar structures. I think the delicate part is a little damaged. And the more times you freeze, thaw, and refreeze, the more likely it is that you’ll end up wearing it a little worse in late winter.
Furby: And this gets worse because of things like climate change.
Weiss: There was a concern that it would be impossible to go back and forth between the scorching heat of winter and the warm season when caterpillars that had been in the extreme cold would thaw and freeze again.
Furby: It also leads to greater ecological impacts.
Weiss: Cordyceps populations, and thus butterfly and moth populations, could be hit hard when these warmer climates impede overwinter survival and prevent them from spending the wintering period as well as they used to.
Furby: And it can affect us more than we think. We already know that important pollinators such as bees and butterflies struggle to survive due to all kinds of human activity.
Weiss: Caterpillars are important just because they’re such cool animals, but they’re also a stage in the life cycle of Lepidoptera, moths and butterflies. they are herbivores. They are food for birds and other organisms. And they’re just part of what makes the world fun to see and live in.
for Scientific Americanof science, quick, I’m Kate Furby.
