Never in my life did I imagine that there could be caterpillars that looked like these. But that’s the great part about being a biologist—or even following biology. As Rudyard Kipling put it, “The wildest dreams of Kew are the facts of Katmandu,” but just invert the places!
From the Scientific American website “Observations“, in a post by Ferris Jabr, we get these wonderful pictures of a caterpillar and its moth. Rarely does a beautiful caterpillar turn into a beautiful adult, but this is an exception. The caterpillar photo immediately below was taken by Gerardo Aizpuru this March on a mangrove tree near Cancun. The creature to the left, looking for all the world like a Gummi Bear, is probably the caterpillar stage of Acraga coa, the lovely orange moth to the right:
Although it’s not 100 percent certain that the “jewel caterpillar” Aizpuru photographed is Acraga coa, it almost definitely belongs to the same family of moths, known as Dalceridae. Scientists have identified around 84 different species of Dalceridae moths, whose larvae are sometimes called “slug caterpillars” because they are so gooey. If you search for “Dalceridae” in Google Images, you’ll see different larvae with the same roly poly bug shape and gumdrop spines, but different colors and patterns. Dalceridae larvae reminded me immediately of nudibranchs, a group of strikingly colored mollusks whose appearance is perhaps best summarized as “trippy.”
Here are some other images from the article. The one below is another view of the caterpillar above; the photo was taken by the famous biologist/naturalist Dan Janzen:
These would seem to be “aposematic” (brightly colored reflecting the fact that the larva is noxious or toxic), but there’s no evidence one way or another right now.
Below is another Dalceridae larva (Credit: artour_a, flickr):
This one is gorgeous, like a coalition of dewdrops (Acraga hamata larva, also of the Dalceridae family, photo again by Daniel Janzen):
What are the crenulated and gelatinous “points” for? The article notes:
Biologists do have some ideas about the function of larvae’s gumdrop spines, however. The glutinous cones break off extremely easily—one can gently tweeze them off or even pull them off by accident—suggestive of the way some lizards’ tails snap off in a predator’s mouth. Janzen says this trick might help the larvae escape from hungry insects and birds, but researchers have not yet confirmed this.
When ants are put together with the caterpillars in the lab, they try to nom them but back off because their mouthparts get gummed up by the gelatinous covering.
Here’s another Dalceridae larva, again photographed by Dan Janzen.