The ghost crab (Ocypode quadrata) is abundant in the beaches of Mexico and in the area of Monte Pío is used as bait to capture fishes. Few works on the behavior ofthis species have been done, and their density in this region of Mexico is unknown. Our objective was to determine population density and to observe the crab's behavior. It's supposed that an increase in the population density will increase the number ofinter-individual encounters producing different responses as a fraction of the participant sizes. To test this hypothesis we calculated in first instance the mínimum quadrant size to estima te the crab's population density, size distribution, activity budgets, and behavioral repertoire; The study area was located within the Tuxtlas Reserve and the beach is 2.8 km long by 30 m width. In order to establish the mínimum sampling area, different square sampling areas ranging from 0.25 to 25 square meters along the beach separated every 100 m were used for counting the inhabited holes in eachquadrant. This procedure was carried out along the crabs daily activity hours. The analysis of these samplings resulted in a square of nine square meters as the minimum sampling area. The activity time for crabs was estimated based on 66 observation covering 24 hours observations. During the sampling months, the ghost crab had an activity distributed in two periods per day between 9:00 to 14:00 hrs and between 22:00 to 24:00 hrs. Results indicate that the distribution of crabs was aggregated in areas where the sand is humid, and that size class dispersionis random. Areas with high influence of ocean waves, or completely dry areas, were not significantly used by crabs. Based on digital video recording we elaborated on the behavioral repertoire of the crab.