Polarization Sensitivity in Reptiles

Abstract

Although there is much information on the homing capacity of reptiles, the role of celestial cues in time-compensated orientation has been studied only in certain freshwater turtles, land tortoises, alligators, snakes and lizards (Chelazzi 1992). The freshwater turtles Terrapene carolina, Chrysemys picta and Trionyx spinifer use celestial cues to orient homeward and may have a sun compass (DeRosa and Taylor 1980), like the land tortoise Gopherus polyphemus (Gourley 1974). Murphy (1981) also found that the sun compass governs the on/offshore movements of juvenile American alligators (Alligator mississipiensis). Some evidence for celestial orientation in displaced snakes has been presented by Gregory et al. (1987). The western diamondback rattlesnake Crotalus atrox has the ability to orient by solar cues (Landreth 1973), and the water snakes Regina septemvittata and Natrix sipedon can use the sun compass for on/offshore orientation (Newcomer et al. 1974). In these snakes a sun compass mechanism based on an internal clock was demonstrated, which capacity seems to be related to orientation to water bodies, not necessarily involved in homing. Sun compass orientation has been demonstrated in the lizard Lacerta viridis (Fischer 1961). However, the homing mechanisms of these reptiles are far from being clarified. The possibility that skylight polarization is used by sea turtles, freshwater turtles, land tortoises, crocodiles, alligators, gavials and snakes has not yet been investigated.