Intertidal Organisms EZ-ID GUIDES


on this species


Mopalia spp. (Mossy, hairy, and woody chitons)

photo of mossy chiton
Copyright © 2005 Mary Jo Adams


Several species from the genus Mopalia can be found on beaches in the Puget Sound area.   They are distinctive in having hairs or bristles sprouting from their girdles.   Chitons from this genus are also unusual because while most chitons are strictly herbivores, the Mopalias consume animal materials including sponges, bryozoans, and hydroids in addition to algae.  


Mopalia muscosa , the mossy chiton (pictured above), reaches a length of about 3-½ inches and the red-brown hairs sprouting from its girdle have a bristly texture.   The valves (overlapping plates) are dull shades of brown, black-olive, or gray and may be overgrown by encrusting organisms or seaweed.   This species is often found out in the open on rocks.


Mopalia ciliata , the hairy chiton, is about the same size as M. muscosa but is more likely to be down in crevices or underneath rocks. The brown hairs on its relatively wide girdle are soft to the touch and it has a distinct notch at the posterior end.   Both the valves and the girdle can vary in color.   The valves may have shades of green, white, red, brown, or yellow with streaks or blotches of white or other colors.   Girdle color can be dark green, pinkish, or white.   This species is an omnivore.


Mopalia lignosa , the woody chiton, can also be colorful.   Valve colors include gray-brown, bluish, or green with feathery markings.   Additionally, rows of pits may be seen on the valves.   The narrow girdle may be cream, brown, or purple brown with light spots from which sprout soft hairs.   The woody chiton grows to a length of about 3 inches and is found on the sides or undersides of boulders.   It feeds primarily on Ulva (sea lettuce).     


This page was created by Mary Jo Adams on 12/6/05.



photo of hairy chiton

photo of woody chiton