Variation of 14 radula characters of 27 Thiaridae species from 5 habitat types in Papua has been investigated. The Thiaridae specimens were collected from Batanta Island, Sorong, Manokwari, Bintuni Gulf, Biak Island, Supiori Island and Jayapura. Scanning Electron Microscope (SEM) was used to observe microscopic Thiarids characters and cluster analysis was employed to group thiarids into 4 groups based on habitats and radula characters. Variations in habitat types (stony reef, sandy rubble, muddy sand, littered mud) had significantly affected the number of cusp (F=24.306, P=0.000), number of lateral tooth (F=9.598, P=0.000), number of tooth line (F=20.320, P=0.000) and length of tooth (F=67.038, P=0.000), and of the number of marginal tooth (F=23.612, P=0.264). Moreover, variations in habitats had also affected the types of radulae. For instance, stony reef habitats were dominated by Thiarids`with rectangular radula types, muddy sand by half-triangular types, sandy rubble by rounded types, and litter-mud by triangular types. Therefore, radula could not be used to identify Thiarids to species level due to its high character variation.