Seanet Mid Intertidal

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Mopalia muscosa (Gould, 1846)
Phylum Mollusca, Class Polyplacophora, Order Chitonida, Family Mopaliidae

Large oval chiton to 80 mm long; valves coarsely sculptured but often eroded or overgrown; dull brown to blackish purple or gray; girdle covered densely with dark brown simple spines.

Common on & under rocks as well as in tidepools, upper mid- to low intertidal zones, exposed & protected outer coast; browses on red algae, Cladophora, bryozoans, hydroids, & barnacles.

Geo Range: British Columbia to northern Baja
Similar species: Nuttalina californica is narrower & more elongate and occurs in more wave-exposed locations.  Mopalia lignosa is similar in shape & size but is gray-green rather than dark brownish-purple.

Image: tiny white spiral  tubes are polychaete Spirobis.