trochus

Trochus is a genus of medium to large sea snails in the family Trochidae, commonly known as top shells or trochids. Members of this genus are marine gastropod mollusks with typically conical, often trochiform shells that have a relatively flat base and a pearly, nacreous interior. The outer surface commonly bears spiral ridges or cords and shows a range of color patterns from solid to mottled, depending on the species.

Distribution and habitat

Trochus species are found in warm seas, particularly in the Indo-Pacific region, including the Red Sea. They inhabit rocky substrates and coral rubble in intertidal to shallow subtidal zones, where they graze on encrusting algae and biofilms.

Ecology and biology

These snails are herbivores that use a rasping radula to feed on algae. Reproduction is typically gonochoric, with separate sexes; many species release free-swimming veliger larvae that eventually settle as juveniles, contributing to dispersal across coastal habitats. Life cycles and larval durations vary by species and environmental conditions.

Species and economic importance

The best-known species is Trochus niloticus, the Nile turban, which has long been harvested for nacre (mother-of-pearl) and used in buttons, jewelry, and decorative inlays. Trochus shells remain economically important in some regions, and selective breeding and aquaculture have been developed to support production. Other Trochus species are collected for decorative shells or maintained in some aquaculture programs.

Conservation

Overharvesting, habitat degradation, and climate impacts have affected certain populations. Management measures in some areas include harvest quotas, size limits, protected areas, and restocking programs to sustain both wild populations and nacre production.