Description

• Cerithium adustum, commonly called the swarthy cerith, is a marine sea snail in the family Cerithiidae. Its solid, elongated shell is typically dark brown to nearly black, sometimes marked with small whitish spots. The shell has a tall pointed spire with several whorls decorated by spiral ridges and rows of rounded nodules. The aperture is often pale or whitish, contrasting with the darker shell. Adults commonly reach about 20–50 mm in length.

Range

• Cerithium adustum occurs in the eastern Pacific, from the Gulf of California and western Mexico southward along the coast of Central America to Ecuador, including the Galápagos Islands. It is recorded from Mexico's Pacific coast and is included among the marine molluscs of the Zihuatanejo region.

Habitat

• It inhabits shallow coastal waters, especially rocky shores, reef flats, and mixed rocky and sandy bottoms. It moves over exposed rock and reef surfaces and may occur among algae and other growth in the intertidal and shallow subtidal zones.

Diet

• Cerithium adustum is primarily a grazer and detritus feeder, scraping algae, microbial films, and organic material from rocks and other submerged surfaces. Its feeding helps process organic matter and algal growth in coastal marine habitats.