Meeting Abstract
One of the outstanding questions in visual ecology is “Do vertebrates really use the polarization of light as a source of visual information?” The majority of evidence we have centers on teleost fish and electrophysiological measurements of polarization sensitivity. However, after almost 60 years of research, no strong evidence exists for any polarization informed behaviour. In other animals, behaviours that rely on the polarization of light fall into two categories, wide field tasks such as navigation, or spatial tasks such as visual signaling and communication. We have discovered that Chromis viridis, a common planktivorous reef fish, uses the polarization of light as wide field information, using a change in the degree of polarization as a feeding cue. Using a combination of on reef studies and controlled tank based experiments we find that as the polarization of light decreases, Chromis respond by leaving their home coral head, exhibiting a greater level of activity and feeding more. This change in polarization occurs naturally as the food load in the water column increases; the greater number of scatterers cause the degree of polarization to decrease. Furthermore, we show that this behavioural response is in part driven by ultraviolet wavelengths.
