One week ago, I was working through my last day of 6 straight days of scouring docks from Maine to Rhode Island looking for and identifying the plethora of organisms present. Along with over 20 marine scientists (including researchers for Oregon, Brazil, and the Netherlands, and our own Seth Goodnight and Christopher Wells), I was cataloging the variety of animals and algae that live and grow on boat docks along the coast as part of an ongoing long term monitoring project (Rapid Assessment Survey). My job was to hunt for worms of all kinds, flatworms, ribbon worms, scale worms, ragworms, feather duster worms, tube-building worms, etc.
Among the species I found, was a scale worm, Harmothoe imbricata, one of the most common worm species in New England. These worms are like the armadillos of the worm world; the soft body of these worms is protected by a series of scales along the dorsal (i.e. top) side of the worm. But what makes H. imbricata unique among worms is the surprising qualities of the scales. The worm is able to shed and regenerate its scales, much like a lizard can drop its tail during an escape from a predator. But not only can the worm shed the scales if grabbed and wiggle to freedom, the scales also create a diversion.
When a worm sheds its scales (for example in response to an attack by a predator, such as a crab), the scales bioluminesce, and release a flash of green light, and then continue to glow where they fall (click here for an image). This serves to warn, distract, and divert predator attention. And for a soft-bodied worm (that is a delicious treat for many other organisms), such a diversion can be the difference between life and death.
If you want to see some incredible photos of polychaete worms similar to those that I’ve been staring at for days, check this site out (note it is a Russian website, but rumor has it if you open it with Google Chrome, it'll translate the page if you want to read and not just look at beautiful photos).
If you're interested, click here for a local Boston news report on this years Rapid Assessment Survey, including video footage of all the scientists working and some underwater shots of what's growing on the docks.
Rivers, T. J., and T. R. Perreault. "Luminescent responses to predation in the scale worm Harmothoe imbricata." Integrative and Comparative Biology 52: e147.