Abstract

We examined the effects of mudballs around burrows and of sex on burrow characteristics (shape, diameter, length, depth and volume) in an underground mating fiddler crab species, Austruca annulipes (H. Milne Edwards, 1837). We investigated 35 burrows with mudballs (males: 20; females: 15) and 34 burrows without mudballs (males: 16; females: 18), and measured their burrow characteristics. Results showed that burrow characteristics did not differ between burrows with and without mudballs. Males built larger-sized burrows with greater volumes, and had more mudballs than females. Crabs built J-, I-, L-, S-and U-shaped burrows, with higher numbers of J-shaped burrows in males, and higher numbers of I-shaped burrows in females. J-shaped burrows were larger with greater volumes, and had more mudballs than I-shaped burrows. For burrows with mudballs, mudball numbers were positively associated with burrow characteristics. This indicates that fiddler crab burrow characteristics are affected by sex, not by the production and presence of mudballs.