Chitons - Mopaliidae

Click on photo to enlarge. Scale line in photo equals 1cm unless otherwise specified.
* Species which are commonly encountered on the beach.

plates Freshwater Bay, WA, intertidal Anacortes, WA, intertidal

Katherina tunicata (Wood, 1815)
Black Katy Chiton *
intertidal to 40m southern California to northern Alaska; Siberia size to 15cm
This is a common intertidal species with a distinct black, leathery appearance. The girdle covers everything but the very center of the plates. It can not be confused with any other species.

Freshwater Bay, WA, subtidal Poulsbo, WA, intertidal

Dendrochiton flectens (Carpenter, 1864)
Painted Dendrochiton
intertidal to 24m southern California to southern Alaska size to 3cm
This species is infrequently found intertidally in the Northwest. It can be red, orange or green with blue, green or gray speckles. There is a single row of 5 long bristles on the posterior end.
(synonyms - Leptochitona flectens, Leptochitona heathii)

preserved specimen, Ketchikan, AK Lopez Island, WA, subtidal

Mopalia egretta Berry, 1919
Egret-Plumed Mopalia
subtidal from 25 to 77m Washington to Alaska size to 2.5cm
This is a somewhat rare species. It can be buff colored to brown to red. The bristles are very fine and branched. The plates have distinctive sculpture.

Oak Bay, WA, intertidal Gabriola Island, BC, intertidal Anacortes, WA, intertidal

Mopalia hindsii (Sowerby, 1847)
Hind's Mopalia *
intertidal to shallow subtidal southern California to central Alaska size to 10cm
This is a somewhat common species. It is usually dark brown to olive-green. It is has a wide brown girdle with a cleft on the posterior end. The plates are almost smooth or slightly pitted. In large specimens the tops of the plates are often eroded. The hairs are numerous but very fine and may be branched on the lower half with extremely fine short bristles. This gives the girdle the appearance and feel of being soft and smooth when wet.
(synonym - Mopalia wosnessenskii)

photographed subtidally
Mopalia ferreirai Clark, 1991
very low intertidal to 18m size to 5cm
northern California to southern Alaska
This species is found in outer coastal habitat and is predominantly subtidal. In its northern range it can occasionally be found on a very good low tide. The plates may be variably colored and patterned. The short bristles (about 2mm) have no groove and are branched with 5 rows of irregular spicules. The spicules can also be sparse.

all Oak Bay, WA, intertidal

Mopalia imporcata Carpenter, 1864
Branch-Haired Mopalia
intertidal to 120m northern Mexico to southern Alaska size to 2.2cm
This species is infrequently found intertidally in the Northwest. It is usually pale brown to dark grayish-brown with some red or white markings. The plates have very defined sculpture with beaded ridges. The hairs are slender and usually curved with numerous branching bristles which stick out from the hair.

Anacortes, WA, intertidal Oak Bay, WA, intertidal Oak Bay, WA, intertidal Gabriola Is., BC, intertidal Oak Bay, WA, intertidal
rare 7-plate specimen

Olympia, WA, intertidal Oak Bay, WA, intertidal Cape Arago, OR, intertidal Thetis Island, BC, intertidal

Mopalia lignosa (Gould, 1846)
Woody Chiton *
intertidal to subtidal northern Mexico to central Alaska size to 8cm
This is a very common species. It is highly variable in color and almost always has the distinctive rays of lines running the length of the chiton. The plates nearly smooth. The hairs are unbranched and usually curved.
(synonym - Mopalia elevata)

Anacortes, WA, intertidal Tacoma, WA, intertidal Mats Mats, WA, subtidal Bremerton, WA, subtidal

Mopalia spectabilis Cowan & Cowan, 1977
Red-Flecked Mopalia
intertidal to 30m northern Mexico to central Alaska size to 7cm
This species is occasionally found intertidally. It has orange-red markings and frequently turquoise blue zigzag lines. The plates may occasionally be completely orange or green. The girdle is often banded. The hairs are densely branched with bristles giving the appearance of thick hairs. It prefers an active current or tidal wash.

Pender Is., BC, intertidal Gabriola Is., BC, found subtidally

Mopalia sinuata Carpenter, 1864
Dwarf Hairy Mopalia
intertidal to 200m size to 2cm
central California to southern Alaska
This very small species is rarely seen. It can be variable in color but is usually brown. It is covered with long, yellowish hairs which are branched the length of the hairs with robust bristles.

plates Deception Pass, WA, intertidal Thetis Is., BC, intertidal Point Whitehorn, WA, intertidal

Mopalia muscosa (Gould, 1846)
Mossy Chiton *
intertidal to 5m northern Mexico to southern Alaska size to 10cm
This is a common species. It has abundant, thick, unbranched hairs on the girdle which feel somewhat stiff. The plates
have coarse sculpture but are often eroded and are a distinct blue color on the underside. The hairs are often covered in grunge.

Oak Bay, WA, intertidal Oak Bay, WA, intertidal Anacortes, WA, intertidal Campbell River, BC, intertidal

Mopalia swanii Carpenter, 1864
Swan's Mopalia *
intertidal to 19m southern California to northern Alaska size to 10cm
This is a fairly common species. It is highly variable in color. Sometimes individual plates may be solid in color. The plates are wide and only moderately sculptured. The girdle is also wide and fleshy and seems almost hairless. Close inspection shows sparse, short, fine hairs which are branched with two rows of bristles on opposite sides of each hair.

Mopalia kennerleyi Carpenter, 1864
Northern Hairy Chiton *
intertidal to subtidal northern California to northern Alaska size to 7.6cm
This is a common species and is highly variable in color. Plates may be solid in color or patterned. Young specimens show sculpture on the plates but on older ones it is diminished. It has numerous hairs on a wide girdle. The hairs are branched with two rows of bristles. This species was once considered Mopalia ciliata, which is now known to only occur from California and southward.

preserved spec., Ketchikan, AK Egmont, BC, subtidal

Placiphorella rufa Berry, 1917
Red Veiled-Chiton
intertidal to 45m size to 5cm
southern Oregon to northern Alaska
This is rarely seen intertidally. It has red plates
and a white girdle making it very distinctive. It
prefers habitats with moderate to heavy currents.

preserved specimen, far west Aleutian Islands, AK
Placiphorella pacifica Berry, 1919
Pacific Veiled-Chiton
deep subtidal to 2000m size to 4cm
central California to southern Alaska
It is milky white with a pale girdle.
There is debate as to whether this species
is synonymous with Placiphorella atlantica.

Oak Bay, WA, intertidal Oak Bay, WA, intertidal Marrowstone Is., WA, intertidal Lion's Bay, BC, subtidal

Mopalia vespertina (Gould, 1852)
Smooth Mopalia *
intertidal to subtidal central California to southern Alaska size to 8cm
This is a fairly common species. The color is usually shades of green or brown but may have variable patterns and blotches of white and blue-green wavy lines. The sculpturing is mild and there are sparse hairs on the girdle giving an overall appearance of smoothness. The hairs are only branched near the base of the hair so largely appear unbranched.
(synonym - Mopalia laevior)

Freshwater Bay, WA, intertidal photographed intertidally photographed in aquarium - underside of raised veil

Placiphorella velata Dall, 1879
Veiled-Chiton
intertidal to 20m northern Mexico to central Alaska size to 6cm
This is infrequently found intertidally. The plates are usually dark in color but may be streaked with other colors. The girdle is longer on the head end. This omnivore grazes algae and also traps prey under its veil.

preserved specimen, Oak Bay, WA Oak Bay, WA, intertidal Oak Bay, WA, intertidal Port Hardy, BC, intertidal

Mopalia cirrata Berry, 1919
Long-Haired Mopalia
very low intertidal to subtidal California to Alaska size to 22mm
This species is infrequently found intertidally in the Northwest. It is variable in color with spots and streaks of color. The longest bristles may be a third the length of the entire chiton. The bristles are branched with a single row of thin hairs set in a groove. The thin hairs are often curled. The plates have distinctive sculpture.

Chitons (Polyplacophora)

Family Mopaliidae