Evolutionary Strategies of the Antennae in Terrestrial Isopods

Helmut Schmalfuss
1998 Journal of Crustacean Biology  
The conquest of terrestrial habitats by the Oniscidea necessitated the development of a moisturemonitoring system. This function is ascribed to the flagellar aesthetascs present on both first and second antennae, in addition to their olfactory function. The extreme diminution of the first antennae prevents them from being inactivated by predator actions, thus guaranteeing the vital monitoring of moisture-gradients in case the second antennae are destroyed by predators. The change from littoral
more » ... ange from littoral to endogean and epigean biotopes has been accompanied by a reduction of flagellar articles in the second antennae. Thus, the terminal gustatory organ can be operated more precisely, meeting the need for exact food localization. The second antennae have additional functions as part of the water conducting system and as a lever to move the animal from a dorsal to a ventral position when overturned. Conglobation provides effective protection for the antennae, and in the superfamily Oniscoidea, the only group surviving under periodic desiccation, the antennal flagellum is cleaned by an obviously indispensable grooming device on the first walking leg.
doi:10.2307/1549516 fatcat:n57lj44k5rg3peyptaigzqqmre