The marine organisms play an important role in biodiversity research. It is one of the basis of aquaculture and also the foundation of ecosystem services. Marine biodiversity data is urgently required, since the global warming is changing the distribution and diversity of many species. Marine environment provide habitats for a wide variety of organisms, it is also supplies many kinds of habitats that support marine life. Habitat loss, overharvesting has had the greatest effect on biodiversity. Suppose to starting hatchery and culture them in ponds knowledge about diversity is essential. Hence, the present study is aimed to know the biodiversity of crabs from Puducherry coastal environment. Totally 47 individual crab species were recorded belonging to 15 families. Maximum crab species were recorded belonging to the family Portunidae than others families.