Recently, I received an email from Kim about a glowing millipede she discovered. Kim is an American living in Thailand, and much to her surprise she found not a millipede, but a bioluminescent centipede, hanging out in her bathroom. (What’s the difference between a centipede and a millipede?) Exhilarated and shocked, she recorded this video of the encounter: http://youtu.be/qLndUElz5hM. The centipede, shown in the inset above, glows (see the 1min, 30sec mark) and displays a pair of luminous green spots (denoted by an arrow in the picture above). I was exhilarated to see the movie as well. I’ve heard about bioluminescent myriapods in Thailand. Most notably, the infamous maeng-kah-reaung (translation: “luminous insect in the roof”) that I first heard about from May Berenbaum’s book, Buzzwords: A Scientist Muses on Sex, Bugs, and Rock 'n' Roll. Not only does the myriapod glow, according to legend, but it also crawls into the unsuspecting victim’s ear and causes tinnitus aurium, or ringing of the ears! In 1950, Yuswadi wrote about this phenomenon in the journal Siriraj Hospital gazette, vol. 2. If you just so happen to have a copy of this article, I’d love to see it. (I haven’t been able to acquire it through ILL and haven’t yet gotten around to calling the National Library of Thailand in Bangkok to request a copy.) In Yuswadi (1950), maeng-kah-reaung is a millipede. (Whenever I ponder the maeng-kah-reaung, I can’t help but think about the Ceti eel from Star Trek II: The Wrath of Khan, which actually seems more like a hellgrammite or antlion.) Anyways, bioluminescent millipedes are not (yet) known from Thailand, while bioluminescent centipedes are indeed. (The natural phenomenon of bioluminescence is rare in myriapods overall; however seems to be a bit more frequent in the centipedes.) The genus Orphnaeus, in the order Geophilomorpha, are bioluminescent centipedes that are distributed throughout the Old World Tropics including Africa, Central and South America, Southeast Asia, and Hawaii. Orphnaeus (pronounced “orf-nee-us”) is in my opinion a better candidate for the maeng-kah-reaung; however, I’m almost certain they do not crawl into folks’ ears. They do, according to Kim, smell like poop. (That said, If any myriapod is a candidate for crawling into ears, it’s centipedes - as they are fast, flexible, and cunning!)

Form and hypothesized function of bioluminescence in Orphnaeus:

Detailed studies of Orphnaeus’ bioluminescence have been published by Harvey (1952) and Anderson (1980), but also see the fantastic review of luminescent myriapods by Rosenberg & Meyer-Rochow (2009). Anderson (1980) reports that Orphnaeus brevilabiatus, upon tactile stimulation, secretes a clear viscous liquid (i.e., slime) that produces a green bioluminescence with a peak wavelength at 510 nm (FWHM = 110 nm, secondary wavelength peak = 480 nm). Because Orphnaeus, and for that matter all centipedes in the order Geophilomorpha are eyeless and apparently blind, the function of bioluminescence as an intraspecific signal (e.g., for attracting mates) is unlikely. As in the eyeless and blind luminous millipedes of California, bioluminescence in Orphnaeus probably serves a role in deterring predators (probably either as an aposematic signal or to distract/deflect predators). What’s cool about Orphnaeus’ luminous secretion is that it’s sticky and adheres to surfaces. As a result, a predator might become distracted by a luminous slime that wipes off the body of the centipede and remains put, thus allowing Orphnaeus to wiggle away unharmed.

Literature cited:

Anderson, J.M. (1980) Biochemistry of centipede bioluminescence. Photochemistry and Photobiology, 31: 179-181.

Berenbaum, M. (2000) Buzzwords: A Scientist Muses on Sex, Bugs, and Rock 'n' Roll. Joseph Henry Press, Washington, D.C., 320 pp.

Harvey, E.N. (1952) Bioluminescence. Academic Press, New York, NY, 649 pp.

Rosenberg, J. & V.B. Meyer-Rochow (2009) Luminescent myriapoda: A brief review, pp. 139 - 146, In: Bioluminescence in Focus - A Collection of Illuminating Essays, Research Signpost, Kerala, India, pp. 385.

Yuswadi, C. (1950) Tinnitus aurium and the luminous millipede. Siriraj Hospital gazette, 2.

Special thanks to Kim for sharing this and also her enthusiastic exploration of biodiversity!