Millipede Fluorescence

Welcome back. How fortunate that, right after I release a blog post, Plants Fluoresce for Bugs, I come across an article about a bug that fluoresces. If you were spun up about carnivorous plants that glow, you’ll go wild about glowing bugs. And these aren’t just any bugs; these are (apologies to entomologists) creepy, crawly millipedes. The glowing carnivorous plants would love to get their tee..uh...love to catch arthropods like these.

Millipedes

This millipede probably doesn’t fluoresce.
(from www.wpclipart.com)

If you’re bothered by all those legs, relax. Baby millipedes have only a half dozen legs and most species don’t grow anywhere near even 400 legs. OK, that’s a lot, but they’re slow. The fast millipedes aren’t millipedes; they’re centipedes. Those millipede wannabes have only one pair of legs for each body segment. Millipedes have two pairs of legs. You’d think centipedes would be satisfied having longer legs and longer antennae.

And it’s not as if a millipede is going to attack you. They’re very docile. Scare them and they curl up. If things get really rough, they can ooze a rather toxic liquid or hydrogen cyanide gas through pores, but that stuff is only a mild irritant to most of us.

The fossil record suggests that millipedes are about the oldest land creature. You might guess that reproduction has played a role. What’s really cool about that is the foreplay. She millipedes coil up if he millipedes come on too quickly, so he has to work at it, rubbing away and maybe humming before she moans Yes! Yes! The rest is kind of graphically private.

Alcatraz Island Millipedes

I’d better get back to fluorescence. This news started on Alcatraz Island, site of the former federal prison, now part of the Golden Gate National Recreation Area, in California’s San Francisco Bay.

In an effort to census rats on the island, National Park Service personnel add a non-toxic fluorescent dye to bait that the rats consume and, of course, return to their surroundings. Since ultraviolet (UV) light causes the dye in the waste to fluoresce, a night-time search with UV lamps (i.e., black lights) provides a measure of the rat population.

In a recent survey by workers and volunteers, the black lights caused the rat waste to glow but so did millipedes. Entomologists at the University of California at Davis ruled out the possibility that the millipedes had sampled the spiked rat bait and determined that non-Alcatraz millipedes of the same species also fluoresced. That species is relatively common in the San Francisco Bay area; it’s just that no one was looking for them with a black light.

Wrap Up

In the overall scheme of things like evolution, it’s interesting to ponder why a nocturnally active millipede has a chemical in its exoskeleton that fluoresces in response to UV light, which you would expect to come from the sun.

While you’re at it, you might also ponder why millipedes of several other species in the same taxonomic family are bioluminescent. They don’t need UV light. They produce their own surprisingly bright white light. You probably missed my blog post on Puerto Rico’s Bioluminescent Bays. Anyway, these aren’t microscopic ocean plankton glowing; these are blind creepy, crawly millipedes.

Thanks for stopping by. You’ll love Tuesday’s photo addendum.

P.S.

- Article on Alcatraz millipedes: http://www.ouramazingplanet.com/4291-glowing-millipedes-on-alcatraz.html
- More about the fluorescent millipedes (and scorpions): http://camastergardeners.ucdavis.edu/?blogtag=Alexander%20Nguyen&blogasset=46848
- Wikipedia review of millipedes: http://en.wikipedia.org/wiki/Millipede
- Millipede facts: http://www.toptenz.net/top-10-facts-about-millipedes.php#ixzz2PPZ7QsDw

Plants Fluoresce for Bugs

Welcome back. I haven’t written about plants--vegetation--since my Lawn and Garden post two years ago. That post received so many rave reviews, I thought I could just rest on my laurels (get it?). But a recent research report has me going botanical again.

The article that tipped me off to the report confused the heck out of me. Fortunately, Cornell Professor William Philpot was available for consultation. We decided the article got enough of it wrong that I’ll forgo listing that article in my P.S.

Before highlighting the research finding, which will tempt you to rush out and buy a to-be-identified plant if you don’t already have one, I’ll start with some not so new but definitely interesting plant facts.

Bugs See the Light

You probably know that plants go shamelessly out of their way, proffering nectar, aroma and color, to attract bugs that might help the plants pollinate. “Color” is the light a plant reflects--green, red, blue. Although you and I get tan, ok, sunburned from ultraviolet light, which I’ll write as “UV,” we can’t see the UV reflected from a plant. But most bugs can.

In fact (here’s the cool part), some plants reflect UV in such a way that the plant looks like a target. The pattern of reflected UV light becomes a nectar guide with a bright outer area surrounding a dark center.

Yellow sorrel reflecting visible (top) and UV light.
(from http://www.sciencedirect.com/science/article/pii/S0030399208002442)

Plant Fluorescence

There’s more. Some plants try harder, though they’re more interested in attracting prey than pollinators. Certain carnivorous plants not only reflect light, they also emit light.

If you’ve gotten this far, the rest will make a lot more sense if you understand that light and color can be described by wavelength. Wavelengths that humans can normally see range from blue, at the short end, through green, up through red at the long end. UV wavelengths are a bit shorter than blue wavelengths, beyond the range of human vision.

Researchers at the Jawaharlal Nehru Tropical Botanic Garden and Research Institute in India found that when selected carnivorous plants were stimulated or excited with a specific wavelength of UV light--light that would be delivered by sunlight--some of the plants exhibited fluorescence. Those plants emitted light at that same UV wavelength as well as at a blue wavelength.

A Blue Glow

Venus flytrap in action. (multiple websites)

Common carnivorous plant traps for catching bugs and small critters include pitfall traps, which have tall rolled leaves that hold pools of digestive liquid (e.g., pitcher plant), snap traps with quick-closing leaves (e.g., Venus flytrap), flypaper traps with sticky stuff (e.g., butterwort), and bladder traps (e.g., bladderworts), which suck in the prey. Plants of each type were tested.

Two of the four types, the pitfall trap and snap trap plants, exhibited the UV and blue fluorescence. When scanned at the UV wavelength, a distinct blue fluorescence appeared on the lids, inner tubes and rims of pitcher plants, and the inner sides of Venus flytraps glowed blue.

To gauge the importance of the fluorescence for attracting prey, the investigators masked the blue emission of pitcher plants and monitored how well they attracted prey over 10 days. The capture success was sharply reduced, suggesting that blue fluorescence ranks up there with nectar, aroma and reflected colors.

Wrap Up

If you’d like to peek at the UV light reflecting from plants or for that matter from anything, you’ll need a special viewer.

To view the blue fluorescence--if the research findings are correct--you’ll need a pitcher plant or Venus flytrap (and bugs). I’m not sure how easy it will be to see. You should be able to boost the fluorescence with a UV lamp (black light) and low-light conditions. Let me know if it works. And thanks for stopping by.

P.S.

- Research paper in the journal, Plant Biology: http://onlinelibrary.wiley.com/doi/10.1111/j.1438-8677.2012.00709.x/abstract
- Good summary article: http://www.bbc.co.uk/nature/21459520
- Nice summary of nectar guides: http://www.cals.ncsu.edu/course/ent591k/nectar_guide.html
- Wikipedia article on carnivorous plants: http://en.wikipedia.org/wiki/Carnivorous_plant
- Link to International Carnivorous Plant Society: http://www.carnivorousplants.org/