COMPETITION TO MATE

It is thought that the claw waving behaviour observed in many species of fiddler crab is driven by competition between males to mate with females during their reproductive season (Murai, Henmi, Matsumasa, Backwell, & Takeshita, 2022). Because of the nature of fiddler crab populations—specifically, their reliance on sociality and visual cues when interacting with other crabs—their colonies are often densely packed with individuals (Rorato, Araujo, Perez, & Pie, 2017). The timing of passing females is unpredictable, given that they must leave their own burrows and wander the shore in search of a mate, so males must compete amongst themselves in terms of appeal and energetic ability to ensure they have the best chance of attracting these rare females to their burrows (Backwell, Jennions, Wada, Murai, & Christy, 2006). This seems to be how claw waving may have evolved: as a way for male crabs to attract females, while also competing with neighbour males for the attention of these females (Murai et al., 2022).