What cardiac frequency tell us about light polarization detection in Neohelice granulata

VERÓNICA PÉREZ SCHUSTER; MELANIE BASNAK; FEDERICO SEVLEVER; JULIANA REVES SZEMERE; GABRIELA HERMITTE; MARTIN BERÓN DE ASTRADA

Congreso; 2nd FALAN congress; 2016

Polarization vision is used by many different species in vital tasks, such as orientation, navigation, prey detection and communication. Neohelice granulata, like other crabs, lives in an environment rich in polarization information. A prior experiment showed that a looming stimulus with the same intensity and spectral light composition that the background, but a 90º degree difference in the angle of linear polarization, evoked animal?s escape response. Thus, this species is able to detect moving stimuli using only polarization cues.We developed a commercial 3-D screen to generate visual stimuli with polarization and intensity contrast. At the same time, we monitor crab?s cardiac frequency as an index of sensory perception. Our goal was to assess if Neohelice uses polarization information to enhance stimulus contrast. When confronted to a looming stimulus crabs responded more and sooner to a stimulus with polarization and slight intensity contrast than to a stimulus with only slight intensity contrast. By other side, when confronted to an edge moving laterally, animals also responded more to an edge with polarization contrast than to an edge without it. These results suggest that crabs can use the information about the polarization of light to enhance the detection of motion stimuli.