Polarization sensitivity and retinal topography of the striped pyjama squid (Sepioloidea lineolata - Quoy/Gaimard 1832).
Coleoid cephalopods (octopus, cuttlefish and squid) potentially possess polarization sensitivity (PS) based on photoreceptor structure, but this idea has rarely been tested behaviourally. Here, we use a polarized, striped optokinetic stimulus to demonstrate PS in the striped pyjama squid, Sepioloidea lineolata. This species displayed strong, consistent optokinetic nystagmic eye movements in response to a drum with stripes producing e-vectors set to 0 deg, 45 deg, 90 deg and 135 deg that would only be visible to an animal with PS. This is the first behavioural demonstration of a polarized optokinetic response in any species of cephalopod. This species, which typically sits beneath the substrate surface looking upwards for potential predators and prey, possesses a dorsally shifted horizontal pupil slit. Accordingly, it was found to possess a horizontal strip of high-density photoreceptors shifted ventrally in the retina, suggesting modifications such as a change in sensitivity or resolution to the dorsal visual field.
Talbot
Christopher M
CM
The Sensory Neurobiology Group, Queensland Brain Institute, and the School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia. chris.talbot@uq.edu.au
Marshall
Justin
J
D000818:Animals; D049832:Decapodiformes / Q000033:anatomy & histology / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology; D017120:Nystagmus, Optokinetic / Q000502:physiology; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000502:physiology; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology*