Polarized light orientation by two Hawaiian decapod cephalopods

1. Two decapod cephalopoda, Euprymna (a sepiolid) and Sepioteuthis (a squid) have been tested for their orientation behavior in a vertical beam of linearly polarized light and in horizontal light intensity patterns. 2. Like many arthropods these mollusks show four preferential swimming directions relative to the e-vector (0°, 90° and ±45°) 3. Horizontal intensity patterns induce only positive or positive and negative phototactic orientation. 4. When polarized light and intensity patterns are presented together the polarized light response predominates. 5. Polarized light vision in these decapod mollusks is a distinct perceptual process showing remarkable convergence wiht this function in arthropods.