Change in Rate of Swimming Contractions and Behavioral Patterns of Polyorchis penicillatus in Response to Different Wavelengths of Light

24 pagesCnidarians have among the most primitive nervous systems, yet they also display diverse behavioral patterns. Previous studies have shown that the hydromedusa Polyorchis penicillatus has a light response in which bell contractions increase as light intensity decreases. The role of wavelength had not been studied previously in relation to behavioral photoresponses for P. penicillatus. This experiment tested 5 wavelengths of light including blue, red, orange, green, and white light, in relation to rate of swimming contraction and behavioral patterns. Darkness was used as a control. Consistently, exposure to blue, red, and white light stimuli resulted in high proportions of the two non-feeding behaviors. Green and orange light stimuli elicited high proportions of the two feeding behaviors. Results are consistent with the idea that P. penicillatus is able to sense different wavelengths through the water column, and therefore engage in feeding behavior in waters with high food concentrations