This is so cool. I read a news snippet in the December issue of Smithsonian Magazine (while hanging out at the optometrist’s office today) that stated that scientists have discovered that nocturnal millipedes in the Great Sequoia National Monument use luminescence (glow-in-the-dark stuff) as a defense mechanism to keep from getting eaten!
It was already known that these millipedes are blind, so the luminescence wasn’t being used to attract mates. To figure out what it was used for, the scientists (from University of Arizona and elsewhere) took a bunch of these millipedes and made some replicates and painted some of the replicates with the luminescent coloring, painted some of the real millipedes with something else (to block the luminescence) and left them in the forest overnight. They found that the real millipedes with blocked luminescence and the non-luminescent replicates were predated by rodents, and the ones with luminescence – real or fake – were left alone. When blind millipedes are disturbed, they generate a hydrogen cyanide toxin (who knew?), so it’s theorized that the luminescence of these animals acts as a defense mechanism – much like the orange and black coloring of monarch butterflies* and the yellow/black coloring of many stinging bees and wasps. I can’t wait to whip this fact out to a bunch of kids then next time I’m talking about bugs. They’ll love it!
*Cool nature fact: Monarch butterflies, like the millipedes are actually toxic to potential predators, so their coloring keeps both them and insect-eating critters safe.
Another cool nature fact: monarchs are toxic due to the fact that their main host plant for egg laying is Milkweed – a plant that produces a toxic, milky liquid which give the monarchs their own toxins (the caterpillars, once hatched from their eggs use the Milkweed as their food source). I recall someone telling me once that the liquid in Milkweed plants contains silicone (don’t know how factual this is), which adds to (or is the direct cause of) the plant’s toxic nature.
Yet another cool nature fact: although the liquid in Milkweed plants is toxic, the flowers, large seed pods and leaves are all edible (when harvested at the correct time – please do some research before eating your first Milkweed plant). Isn’t nature awesome??!!
“The longer I live, the more my mind dwells upon the beauty and wonder of nature.”
– John Burroughs
Really interesting stuff! It’s so weird to think that a bug developed luminescence as a defense mechanism. How does this happen. Wow.
Yeah, I wondered the same thing – and yet it makes so much sense. The only other defense mechanism I can imagine for a nocturnal creature that’s that small would be some kind of smell. But even some animals that do use smell as a defense – I’m thinking particularly of skunks – still have a visual warning first: their black and white coloring.
And I forgot to mention in the post that at the Smithsonian link they have a picture of the glowing millipede: http://blogs.smithsonianmag.com/science/2011/09/the-millipede-that-glows-in-the-dark/
That’s awesome!
I totally explained the milkweed/monarch thing to someone in a “isn’t nature amazing?” conversation yesterday. I especially love how viceroy butterflies have evolved to mimic the monarch, so predators avoid them too, even though they aren’t actually toxic. I know digitalis (the heart medication) has the same properties as milkweed. It may even be derived from milkweed (at least originally?)
We did a bioluminescence lab in college that involved luciferase, the compound that makes fireflies glow. Is that the same compound found in these millipedes? I know the luciferase is toxic.
You know, you’d think some clever insect-eating creature would have caught on to the viceroy by now…