Function of waving variation in Leptuca pugilator

Fiddler crabs use signaling as a prevalent part of their life histories. The waving of the major (enlarged) claw serves as a signal for attracting mates and in territorial interactions with other males. These waves vary considerably in structure and pattern and although their general use in mate attraction and male competition has been established, the possible function of different types of waves used in different social contexts has not been widely studied. In this study, we investigate the possible functional significance of predominant wave types by examining the behavioral context in which they are performed by male Leptuca pugilator (Atlantic Sand Fiddler Crab) in South Carolina salt marshes. We found that 2 wave types occurred most frequently. “D-waves” were most common when facing other males and were influenced by the distance to the nearest neighbor, while “up-and-down waves” were most common when females were present and when the focal crab was facing a female. Our findings suggest that these 2 waves may, respectively, be used primarily in
male–male competitive interactions and in attracting mates.

Methods
Data were collected via video observations of naturally waving fiddler crabs.