Living Painting on Intertidal Rocks - The Lined Chiton, Tonicella lineata (Wood, 1815)

One of the most colorful intertidal organisms of the West Coast of North America is a small rock-hugging species of mollusc known as the lined chiton. Actually, there are at three or more species of lined chitons (Tonicella) living along wthe West Coast, but Tonicella lineata (shown here) is the most common.

Chitons make up a distinct class of the Phylum Mollusca, Class Polyplacophora (meaning "bearing many plates") (formerly known as Class Amphineura). These animals are generally herbivores (there is one interesting species of carnivore on the west coast), that scrape their algae food off of rocks using a flexible, toothed belt-like rasping organ known as a radula. The teeth of the radula are hardened with iron and manganese minerals extracted from the water during tooth formation. These minerals mske the tooth so hard that it can perform the scraping chore without wearing down too quickly. Amazingly, the lined chiton feeds primarily on very hard encrusting red algae that cover rocks in the lower intertidal and shallow subtidal areas.

Tonicella lineata	chiton radula

For a great teaching tool about molluscs that features chiton reproduction and life history, see our program, Branches on the Tree of Life: Molluscs.