Context-dependent orientation cues in a supratidal amphipod

Abstract

Most mobile animals rely on orientation cues for either long-distance migration or to move shorter distances on a daily basis. Supratidal amphipods in the northern Gulf of Mexico regularly use orientation cues in both water and on dry sand to return to their home in seagrass wrack. I manipulated the presence of visual and magnetic cues in both water and sand. Visual cues were important for orientation in water, but magnetic cues were important on dry sand. The use of orientation cues by amphipods is context-dependent and suggests that some cues may be more reliable in different environments. Casey P. terHorst is now at Kellogg Biological Station, Michigan State University, Hickory Corners, MI, USA.