Functional morphology of the cuticular terraces in burrowing terrestrial brachyuran decapods

Observations on Gecarcinus lateralis and Ocypode quadrata from Bermuda show that their cuticular terraces are not functional as burrowing sculptures, as previously assumed. Instead, they increase the friction against the walls of the burrow when the animal wedges itself to avoid being extracted by predators. No significant increase in the number of terraces takes place during growth in the size interval available for this study. This is different from the situation described as usual in burrowing decapods, and is rather similar to that of crevice-dwelling crabs. The distribution of terraces and their ontogenetic pattern, therefore, are not reliable indicators of the life habits.