Discrete modulation of antipredatory and agonistic behaviors by sensory communication signals in juvenile crayfish

Abstract

We investigated how the exchange of sensory signals modulates the individual behaviors of juvenile crayfish in an anti-predatory context as well as during intraspecific agonistic encounters. We first compared crayfish housed in total sensory isolation or in pairs with access to chemical and visual cues. After one week of housing, we analyzed their individual responses to a visual danger signal while they were foraging. We found that crayfish previously housed in pairs with exchange of sensory signals responded to a simulated predator attack predominately with freezing behavior, whereas animals deprived of all sensory communication mostly responded by performing escape tail-flips. Next, we used the same housing conditions in-between repeated fights in pairs of crayfish. Aggressive and submissive behaviors increased in subsequent fights both after total isolation and after exchange of olfactory and visual signals. Thus, unlike responses to simulated predator attacks, intraspecific agonistic behavior was not modulated by exposure to the same sensory signals. However, when we tested the effects of olfactory or visual communication independently, aggression increased dramatically after the exchange of olfactory signals, which also led to a high number of rank reversals in second fights, suggesting a destabilization of the original dominance relationship. Exposure to visual cues during the one-week separation, however, produced the opposite effect reducing agonistic behaviors and rank reversals. These findings demonstrate that exchange of sensory signals modulate future anti-predatory decision-making and intraspecific agonistic behaviors discretely, suggesting that the effect of these signals on shared neural circuitry is context-dependent.