Meeting Abstract

105.1  Sunday, Jan. 6  Luminescence reduces mortality of the scale worm Harmothoe imbricata when attacked by crustacean predators. RIVERS, TJ*; LIVERMORE, JC; PERREAULT, TR; Bowdoin College; Bowdoin College; Bowdoin College trivers@bowdoin.edu

The luminescent scale worm Harmothoe imbricata is found in abundance in the intertidal and subtidal habitats of coastal Maine. Luminescence occurs in the elytra (scales), which emit light when both attached and detached from the body. Worms can also exhibit whole-segment autotomization, with the posterior half luminescing and the anterior half staying dark, presumably to escape and regenerate the lost segments. Although the luminescence has long been postulated to provide an increase in survivability upon predation attempts, the role luminescence plays on survivorship has yet to be quantified. Using low-light CCD cameras with infra-red (IR) illumination, a night vision device with an IR barrier filter, and a photomultiplier, we recorded the interactions of dark-adapted H. imbricata with crustacean predators having different visual capabilities. The eyes of green crabs (Carcinus maenas) and American lobsters (Homerus sanguineus) were painted with a matte-black or clear polish, or left unpainted. We found H. imbricata were 15% more likely to escape after the first attack eliciting luminescence with visually unimpaired predators than with blind predators. Upon multiple attacks by the same predator, the trend increased, with worms escaping 25% more from predators able to see the luminescent displays than from blind predators. These data indicate that the luminescent behavior of the worms does play a role in escaping predation. In order to further determine the role of light for defense, we will discuss how computer-controlled LED displays mimicking scale worm displays affected predator behavior in the absence of any other sensory modality.