Abstract
The gastropod is one class of the Mollusca phylum using the abdomen as the leg. Generally gastropods are crawling on the bottom of the waters and submerged in the mud and are often called epifauna and infauna gastropods. Research on diversity of epifauna gastropods in the littoral zone has been done in Mesjid Raya, Aceh Besar District. This research aims to determine the diversity of gastropod species based on the substrate types (coral reef, muddy and sandy). The exploratory method by using transect line was used in this study. In each substrate, a line transect was drawn for five transects with a length of 50 m. The transects were started from the tidal line. The distance between transects were 50 m. Each transect was made in 10 sampling plots measuring lm × lm, and the distance between plots was 5m. The gastropods were collected directly and without damaging the substrates. The epifauna gastropods obtained was put into a sample bottle and preserved using 70% alcohol. The results showed that 23 families and 54 species of epifauna gastropods were identified. The number of species of gstropods was found in the sandy and muddy substrate more than in the sandy and corral reef substrate, but the highest diversity index was found in the sandy substrate, meanwhile the lowest diversity was found in the coral reef substrate. The highest species density was obtained on Rhinoclavis aspera.