Bioluminescent Millipede, Which Oozes Cyanide, Uses Green Glow to Warn Off Predators

Posted on September 26, 2011

A University of Arizona-led research team has discovered that bioluminescent millipedes use their glow as a warning signal to nocturnal predators. The millipedes back up their warning by oozing toxic cyanide and other foul-tasting chemicals. The millipede species, Motyxia sequoiae, is found in certain mountain regions in California.

Paul Marek, a research associate in the UA's Department of Entomology and Center for Insect Science, and his team have provided the first evidence gained from field experiments of bioluminescence being used as a warning signal. Charity Hall, Marek's wife and a metalsmith, made a bronze cast of a millipede, which the team used to create molds to make 300 fake millipedes out of clay. Half of them were painted with a glow-in-the-dark paint. The group took the clay millipedes to Giant Sequoia National Monument in California, where they set them on the ground along a transect line, spaced five meters (16 feet) apart. Glowing and non-glowing individuals were distributed in random order to avoid sampling bias.

The researchers also put out live millipedes. The live millipedes were divided into two groups. One group was covered with paint to conceal their natural glow. The other group was left untreated. The live millipedes were tethered with a fly-fishing knot so they wouldn't walk out of the experiment.

The next morning the researchers found that four times as many non-glowing millipedes showed evidence of attacks compared to their glowing peers. Non-luminescent models were also attacked twice as often in a daytime study than those that glowed.

The precise biochemical mechanism by which the millipedes glow in the dark is not yet completely understood. Marek says, "For now, all that we know is they use a different mechanism than fireflies or glowworms, which use an enzymatic reaction. The millipedes have a photoprotein that is similar to the Green Fluorescent Protein of the jellyfish Aequorea victoria. It is thought to be activated by calcium and energy-rich compounds in the cell to create the glow."

Here is a video about the interesting experiment. Take a look:

The research paper about the experiment was published today in Current Biology.

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