Shell tall-spired, usually with flared outer lip and reflexed siphonal canal. Operculum paucispiral. Males aphallate; females with open pallial gonoducts. Biology. Cerithiids are generally understood to be detritus browsers and grazers. As in other groups that feed at low trophic levels, the species are often abundant in their habitat. Anatomy for the family was summarized by Houbrick (1988:116), who indicated about 25 genera and hundreds of species, most of which occur in tropical and subtropical waters.