The population dynamics depend on environment and habitat stability and environmental conditions are the main element effecting biodiversity and richness. The main objective of this study was to assess biodiversity of intertidal crabs in Chabahar bay. During this research TOM, moisture, density, dominance, richness and evenness were measured. Sampling were carried out at 3 stations: Tiss, Jazireh Kharchang and Konarak in July 2009. Totally, 7 species were recorded belonging to the family Ocypodidae. The results of biodiversity indices in 3 Stations revealed that Jazireh Kharchang with 5 species and Konarak with 1 species have the highest and lowest diversity, respectively. The percentage of TOM and grain size showed significant differences between the 3 stations, while the highest TOM and lowest sand percentages were observed in Jazireh Kharchang
