Chiton Vert

Overview

Rhyssoplax olivacea is a common marine chiton found throughout the Mediterranean Sea. This mollusk is typically identified by its oval shape and a series of eight articulated dorsal plates, which often display a greenish-brown hue.

Distribution & habitat

This species is primarily endemic to the Mediterranean, though it has been reported along the coasts of Portugal, Morocco, and parts of Brazil. It favors intertidal rocky environments, particularly areas exposed to wave action. Because it is photophobic and has limited resistance to drying out, it is most frequently found clinging to the undersides of rocks or in shaded crevices during low tide.

Appearance

These chitons generally reach lengths of 20 to 40 mm. Their shell consists of eight independent, granular plates that are arched with a distinct central keel. The plates are decorated with a pattern of horizontal, vertical, and diagonal ridges. While commonly olive-green, their coloration is highly variable and can include shades of yellow, brown, red, or black. A large, granular girdle surrounds the valves, often marked by alternating light and dark radial bands.

Biology & behavior

Rhyssoplax olivacea is a slow-moving grazer that crawls across rocky surfaces to feed when submerged. Its radula, used for scraping algae, contains teeth reinforced with magnetite, one of the hardest biological materials. Research indicates that the species exhibits allometric growth, with its internal skeletal structures and radula adapting to its body size as it matures.