Polarization sensitivity and retinal topography of the striped pyjama squid (Sepioloidea lineolata– Quoy/Gaimard 1832)

Abstract

SUMMARY 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.

Maturation of polarization and luminance contrast sensitivities in cuttlefish (Sepia officinalis)

“…At 30days, at least half of the cuttlefish responded to the polarization pattern at all velocities, except for the highest rotation rate of 130degs -1 (Fig.3). Previous studies demonstrated an OMR to polarized stripes in other mature cuttlefish species, using a velocity of 12degs -1 and with stripes 2.5cm in width (Talbot and Marshall, 2010a;Talbot and Marshall, 2010b), which raises the possibility that our cuttlefish would have responded to slower rotating patterns as well. However, Darmaillacq and Shashar (Darmaillacq and Shashar, 2008) did not succeed in eliciting an OMR to a polarized pattern in adult Sepia elongata, using velocities ranging from 34 to 178degs -1 , although S. elongata possess orthogonal photoreceptors in their retina suggesting the ability for polarization detection.…”

“…These apparently puzzling results could be explained by the higher speed of motion for the rotating pattern compared with the nearly stationary prey. In such a case, using a slowly moving pattern (Talbot and Marshall, 2010a;Talbot and Marshall, 2010b) might elicit stronger responses even in very young animals. Alternatively, these apparently contradicting results can be due to differences in the size of the receptive fields of the retina needed to detect each type of signal.…”

“…OMR induced in juvenile Sepia officinalis improved in luminance-contrast-based visual acuity from a minimum separated angle of 2.5deg in cuttlefish measuring 1cm to 0.5deg for cuttlefish measuring 8cm (Groeger et al, 2005). OMR was also used to examine PS in adult cuttlefish of different species, but has not yet been studied in hatchlings (Darmaillacq and Shashar, 2008;Talbot and Marshall, 2010a;Talbot and Marshall, 2010b). Newly hatched cuttlefish are able to visually discriminate between different crab phenotypes, suggesting good detection of prey based on luminance contrast (Guibé et al, 2012).…”

The pupillary light responses of animals; a review of their distribution, dynamics, mechanisms and functions

“…In squid, on the other hand, the constricted pupil is often crescent-shaped (McCormick & Cohen, 2012;Talbot & Marshall, 2011;Chung & Marshall, 2017; Fig. 18C), but can also be either a horizontal (Talbot & Marshall, 2010) or a vertical (Matsui et al, 2016) slit.…”

“…18E). It seems different regions of this complex pupil are controlled locally with, for example, only the back or the front of the W dilating when the animals fixate objects of interest, such as approaching divers, in different directions (Talbot & Marshall, 2010).…”