Spatial distribution and population structure of Ocypode quadrata (Fabricius, 1787) were studied at Pinhal beach, Rio Grande do Sul, from November/91 to December/93. Analysis of frequency distributions of the ghost crab population was based on indirect census, with burrow diameter measurement. It was identified the presence of two age-groups, with the possible presence of a third one. The maximal life span was estimated to be about 3 years. Burrow diameter/carapace width, lenght/width and weight/width relationships were estimated from samples obtained by excavating burrows and individual capture by traps. These relationship were ajusted by the following equations, respectively: DT = 0,6648 + 1,0013.L; C = 0,77.L1,02; and P = 0,0004.L3,0876 (DT is burrow diameter; C is the carapace lenght; L is the carapace width; and P is the weight). Spatial distribution analysis was performed based on distance and altitude to water line. These crabs dig burrows preferentialy in the central large range of the beach, although having possibility of migration at adverses conditions. Burrow shape also was analysed.
Ocypode quadrata; ghost-crab; population structure; burrows
