Katharina tunicata
black katy
(Also: leather chiton)

Common along Pacific Northwest Coast. Especially common in the San Jaun Islands and Strait of Jaun de Fuca (Niesen 1997).

Katharina tunicata is found in the middle and upper zones of the rocky intertidal, and can withstand hard wave action. This chiton is often seen near the borders of mussel clumps. (Niesen 1997; Mohler 1997)

Katharina tunicata is a medium sized chiton, with an average length of 7 cm. Its black girdle almost completely covers the eight whitish plates, leaving a diamond shaped pattern down the dorsal side. The plates are sometimes overgrown with algae, so they will appear green (Mohler 1997). Like most chitons, K. tunicata is oval shaped, but when removed from the rock it will ball up (Karleskint 1998). The underside of K. tunicata is commonly peach colored,and houses the gills and mouth. The foot is surrounded by mantle and is usually darker orange.

Katharina tunicata crawls around with its foot, like a snail, while in the water, but when the tide goes out it adheres to the substrate until the water returns. The mantle margin and foot hold K. tunicata firmly to the rocks, even in areas of high wave action. Chitons feed by scraping their tongue or radula across the rocks for algae (Dorit 1991). Katharina tunicata is preyed upon by the common sea star, Pisaster ochraceus (Morris 1983).

Katharina tunicata is an herbivore. Its main food sources are brown (Phaeophyta) and red (Rhodophyta) algae (Mohler 1997).

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