dc.description.abstract | Carita beach is one of a beach ecosystem that has variety of substrates. Substrates were dominated by sand and corral reef flat. There were vegetations such as seagrass and seaweed. The aim of the research was to know species richness and diversity of Bilvave and Gastropod in Carita beach, Pandeglang, Banten. The research was conducted on May 2008. Molluscs sample were collected from 4 stations randomly by using quadrat method. There were 34 species molluscs that had been observed, 3 species belong to Bivalves and 31 species belong to Gastropods. The highest Important Value Index (IVI) of all station was found in Donax cuneatus with 55.21%. The lowest IVI was found in thirteen species of Bivalve and Gastropod with 0.83%. The diversity index (H’) ranged from 0.130 to 2.216, the evenness index (E) was 0.072 to 0.717, and the dominant index (C) was 0.198 to 0.960. The highest diversity index (2.216) was found at station 4 and the lowest (0.130) was at station 1. The similarity index ranged from 0 to 0.744. Key word : diversity, quadrat method, Carita beach | id |