Polarization contrasts and their effect on the gaze stabilization of crustaceans

Many animals go to great lengths to stabilise their eyes relative to the visual scene and do so to enhance the localisation of moving objects and to functionally partition the visual system relative to the outside world. An important cue that is used to control these stabilisation movements is contrast within the visual surround. Previous studies on insects, spiders and fish have shown that gaze stabilisation is achromatic (= ‘colour-blind’), meaning that chromatic contrast alone (in the absence of apparent intensity contrasts) does not contribute to gaze stabilisation. Following the assumption that polarization vision is analogous in many ways to colour vision, the present study shows that five different crustacean species do not use the polarization of light alone for gaze stabilisation, despite being able to use this modality for detecting predator-like objects. This work therefore suggests that the gaze stabilisation in many crustaceans cannot be elicited by the polarization of light alone.