Predators and prey examining flashing as a signal in Ctenoides ales, “disco” clams

Meeting Abstract

99-6  Wednesday, Jan. 6 14:45  Predators and prey: examining flashing as a signal in Ctenoides ales, “disco” clams DOUGHERTY, L/F*; NIEBERGALL, A/K; CALDWELL, R/L; University of California, Berkeley; University of California, Berkeley; University of California, Berkeley

The “disco” clam Ctenoides ales is known for its vivid flashing display which results from light-scattering silica nanospheres. Hypotheses regarding the fitness value of the flashing include the luring of phototaxic prey items or predator deterrence through aposematism. The effect of the light display on planktonic prey items was examined during three experiments. First, in situ water samples were taken while SCUBA diving from inside individual clams during high-light (flashing visible) and low-light (flashing not visible) conditions. Second, plankton samples were collected offshore and then exposed in the laboratory to artificial clams made from C. ales valves with LED strips of light that were off, on, or flashing. Finally, additional plankton samples were exposed to video playback with two lines; one constant, and one flashing, which mimicked the spectra and the flash rate (Hz) of the clam. All samples were compared against each other and controls, and examined for plankton volume and diversity. Results indicated there was no trend toward higher prey numbers in any of the treatments or sample groups. To test aposematism, predators were identified using video analysis, underwater observation, and dead valve collection. Valve damage type was linked to potential predators, and laboratory interactions were filmed when possible. Predator analyses are ongoing, including the study of potentially volatile sulfuric compounds present in the tissue of the clam.

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