Comunicação visual em caranguejos chama-marés: efeitos da coloração na sinalização sociossexual e predação

Abstract

Visual communication occurs through signals emitted by a signaller aiming to modify the receiver's behaviour. For conspecifics, these signals can increase mating opportunities and prevent unnecessary conflicts but may also attract the attention of predators. In fiddler crabs, females detect color signals during mate selection, yet the relationship between these signals and individual or reproductive quality, as well as their role in affecting predation costs, remains unclear. This study aimed to investigate the role of coloration in socio-sexual signalling and prey-predator interactions. We conducted laboratory analyses using spectrophotometry, photography, and force sensors to extract variables related to color, shape, and strength. Additionally, field behavioural studies were conducted to assess competitive ability, attractiveness during mate selection, and effects on predation. Our results showed that visual signals from claws and carapaces, particularly nuptial coloration, serve as reliable indicators of individual and reproductive quality. Furthermore, body coloration plays a critical role in the deflection mechanism, diverting predatory attacks toward non-vital body regions. We conclude that the visual ecology of fiddler crabs is shaped by distinct evolutionary pressures, with body coloration playing a crucial role in their adaptation and evolution.