Habitat influences the evolution of antennae and antennule size in freshwater crayfishes

Abstract Sensory structures are crucial for animals to detect environmental stimuli. While vision and hearing are well-studied due to their importance in human communication, other senses like chemical detection and touch are less understood, especially in animals from diverse habitats such as caves. Crayfish, diverse crustaceans inhabiting various environments, rely heavily on chemical and mechanical senses. In this study, we examined 1526 specimens across 93 crayfish species from different sensory environments, measuring the relative lengths of their antennae and antennules as proxies for mechanosensation and chemosensation. Our findings show that sensory environment significantly influences the relative length of these structures. Cave-dwelling species had the longest antennae and antennules, while burrowing species had the shortest, probably due to the confined nature of burrows. This study underscores the importance of antennae and antennules in crayfish biology, though further research is needed to fully understand their functional significance across species and environments.