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 lip has a dense collection of silica nanospheres, which are highly scattering, and the other side of the mantle tissue is absorbent. Experiments were conducted to determine the behavioral function of the flashing. One hypothesized fitness value is aposematic signaling; the idea that the photic display is meant to deter predators. This hypothesis relies on two fundamental pieces of evidence: that the clams react to the presence of potential predators and that their tissue is noxious or toxic to predators when consumed. To test the behavioral component of aposematism, the clams were presented with stimuli of a looming predator. 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 the stimuli. To determine the palatability of the tissue, scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) was performed on prepared tissue samples. The presence of sulfur was identified in mantle and tentacle tissue. Volatile sulfur compounds have been known to act as chemical defense mechanisms in nature, including guava plants, snails and algae. To test for sulfuric excretions, electrospray ionization mass spectrometry (ESI-MS) was performed with rinse water from clams that were calm (not in the presence of a predator) and disturbed (attacked by the mantis shrimp, Odontodactylus scyllarus, until shell breakage occurred). Unique peaks were identified in the ESI-MS of the disturbed rinse that did not exist in the calm clam rinse, and analyses are ongoing.
