Mopalia lignosa (Gould, 1846) 

Common name(s): 

Phylum Mollusca
 Class Polyplacophora
  Order Neoloricata
    Suborder Lepidopleurina
     Family Mopaliidae
Mopalia lignosa, San Simeon, CA
(Photo by: Dave Cowles, 1997)
Description:  This chiton has a hairy girdle all around.  The girdle is about the same width all around, and all plates are about the same width.  The girdle hairs are not as long as the girdle is wide.  The lateral areas of plates 2-7 are separated from the middle region by a ridge or series of small tubercles.  The surface of the plates have longitudinal rows of small pits visible with low magnification, especially in the central areas.  Plates have streaks and lines of brown, purple-brown, mahogany, or occasionally white.  Girdle is cream, brown, or purple-brown above and orange below.

How to Distinguish from Similar Species: The hairs are flexible, not stiff and thick as in Mopalia muscosa.  Other Mopalias have longer hairs or have tubercles instead of pits on the plates.

Geographical Range:_Prince William Sound, Alaska to Point Conception, CA

Depth Range: Middle and low intertidal

Habitat:  Sides or bottoms of large boulders on open coast

Biology/Natural History: This species is usually under rocks, and begins crawling when the rock is turned over.  They are the fastest crawling chiton I have seen (are those racing stripes on the plates?)  Feeds on many types of algae, especially diatoms and Ulva.  Sense light with aesthetes in plates.

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Dichotomous Keys:
Kozloff 1987, 1996
Smith and Carlton, 1975
Flora and Fairbanks, 1966

General References:
Morris et al., 1980
Niesen, 1994
O'Clair and O'Clair, 1998
Kozloff, 1993

Scientific Articles:

General Notes and Observations:  Locations, abundances, unusual behaviors:

Another view of Mopalia lignosa.  Note the hairs between the plates.  Photo by Dave Cowles, San Simeon, CA 1997

Authors and Editors of Page:
Dave Cowles (2005):  Created original page