Grooming and agonistic behaviors in the semi-terrestrial crabs Ocypode quadrata (Fabricius, 1787) and Minuca (Uca) burgersi (Holthuis, 1967) (Decapoda: Brachyura: Ocypodidae).

This article focuses on the grooming behaviors of two semi-terrestrial crab species, the ghost crab (Ocypode quadrata) and the fiddler crab (Minuca (Uca) burgersi), comparing their grooming time budgets, body regions groomed, and grooming mechanisms to those of fully aquatic crustaceans. Laboratory observations revealed that both species groom sensory and locomotory structures such as eyes, maxillipeds, and pereiopods, but have significantly lower grooming time budgets (0.526% for ghost crabs and 0.895% for fiddler crabs) than fully aquatic crustaceans. Ghost crab grooming decreased during agonistic interactions, supporting grooming as a secondary behavior, and individuals exhibited thanatosis (playing dead) to avoid injury during fights. The study suggests that environmental differences, such as reduced water exposure and fouling pressures, influence grooming behaviors in semi-terrestrial crabs, highlighting the need for further detailed research on their grooming ecology.