Meeting Abstract
Ctenoides ales is an Indo-Pacific bivalve that has a vivid flashing display caused by the rapid movement of the mantle lip. One side of the mantle tissue has a dense collection of silica nanospheres, which are highly reflective, and the other side of the mantle tissue is absorbent. Experiments were conducted to determine the behavioral function of the flashing. Hypothesized fitness values included phototaxic prey luring, aposematic signaling, and/or conspecific recruitment. To test prey luring and aposematism, the clams were presented with stimuli of food (phytoplankton) and a looming predator, respectively. Their reactions were filmed and the flash rate was analyzed 5 seconds before and after the stimuli. Results showed a significant increase in flash rate with both stimuli. To test conspecific recruitment, nine tanks were divided in half using either transparent or opaque barriers. The experimental side of the tanks housed a C. ales, and the stimulus side of the tanks housed either another C. ales, a video of C. ales, the non-flashing congener C. scaber, a rock, or nothing (control). This setup allowed both visual cues (the ability to see another C. ales flashing, see only an object, or see nothing) and chemosensory cues (barriers either allowed water flow or prevented it) to parse out cues used in settlement position. Distance and orientation toward the stimulus was recorded every hour for 5 hours. Preliminary results indicate that both chemosensory and visual cues caused the experimental C. ales to move closer to the C. ales stimuli than the control. To investigate ecological variations in flash rate, light trials were conducted in different intensities of blue light to mimic various depths. Results showed no significant difference in flash rate between light intensities. Behavioral analysis is ongoing.
