Chitons - Mopaliidae

Boreochiton beringensis (Yakovleva, 1952)
Northern Red Chiton
very low intertidal to at least 30ml size to 35mm
northern BC to Bering Sea
This species may have red, green or blue patches on its plates.
(previous name - Tonicella beringensis)

typical intertidal appearance a freshly dead specimen photographed subtidally photographed intertidally

plates juvenile

Cryptochiton stelleri (Middendorff, 1847)
Giant Pacific Chiton or Gumboot Chiton *
intertidal to 20m size to 35cm
southern California to northern Alaska; Japan
This is a fairly common intertidal species and is the largest chiton species in the world. The girdle completely covers the plates.
The disarticulated plates are often called "butterfly shells".
(previous name - Amicula stelleri)

plates photographed intertidally

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.

preserved specimen photographed subtidally photographed intertidally

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 long bristles on the posterior end.
(synonyms - Leptochitona flectens, Leptochitona heathii)

preserved specimen photographed subtidally

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.

preserved specimen all photographed intertidally

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.

preserved specimen all photographed intertidally

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.

preserved specimen all photographed intertidally rare 7-plate specimen

Mopalia kennerleyi Carpenter, 1864
Northern Hairy Chiton *
intertidal to subtidal northern Mexico 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. 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 specimen photographed intertidally

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. 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.

preserved specimen photographed intertidally found subtidally

Mopalia sinuata Carpenter, 1864
Dwarf Hairy Mopalia
intertidal to 200m central California to southern Alaska size to 2cm
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 photographed intertidally

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. The plates
have coarse sculpture but are often eroded and are a distinct blue color on the underside.

preserved specimen photographed subtidally

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
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.

first three photographed intertidally photographed subtidally

Mopalia vespertina (Gould, 1852)
Smooth Mopalia *
intertidal to subtidal central California to southern Alaska size to 8cm
This species is occasionally found intertidally in the Northwest. 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 the hairs mainly appear unbranched.
(synonym - Mopalia laevior)

preserved specimen 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 may be reddish-brown or yellowish. This omnivore grazes algae and also traps prey under its veil.

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 streaks of lines running the length of the chiton. The plates nearly smooth. The hairs are unbranched and usually curved.
(synonym - Mopalia elevata)

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.

preserved specimen photographed subtidally

Tonicella insignis (Reeve, 1847)
White-Line Chiton
intertidal to 50m size to 6cm
northern Oregon to northern Alaska
This species is rarely found intertidally. It is reddish-brown with lighter-toned wavy lines across the width of the plates. The girdle is light brown.

Tonicella lineata (Wood, 1815)
Lined Chiton *
intertidal to 90m southern California to northern Alaska, Japan & Siberia size to 5cm
This is a very common intertidal species. The background color is orangish but can range from pink-orange to brown-orange. Wavy bluish-white lines run across the sides of the plates which are edged in reddish-brown. The lines along the head and tail plates may be wavy, but are not usually zigzagged. The lines on the head and tail plates will also be edged in reddish-brown. Some plates may be a solid color, usually a reddish tone but sometimes blue. The girdle is banded and also may vary in its colors. Very young specimens can be hard to distinguish from T. undocaerulea, when the pattern features are not yet well developed.

Tonicella rubra (Linnaeus, 1767)
Northern Red Chiton
intertidal to 145m size to 22mm
California to Arctic; in Atlantic - Connecticut and northern Europe to Arctic
This is rarely found intertidally in the Pacific Northwest. The plates are light tan with red to orange-red markings. The plates may also be uniformly reddish. The girdle is covered in minute scales which do not overlap.
(synonyms - Boreochiton ruber, Ischnochiton ruber)

Sitka, AK, preserved specimen Freshwater Bay, WA, subtidal Tongue Point, WA, subtidal

Tonicella undocaerulea (Sirenko, 1973)
Blue-Line Chiton
intertidal to 50m southern California to central Alaska size to 5cm
This is occasionally found intertidally. It has a light orangish-pink background, and may occasionally be solid in color. Blue to white wavy lines run along the sides of the plates. There may be streaks of maroon edging some of the lines. The blue lines on the head and tail plates are distinctly zigzagged and are not edged in maroon. The girdle is banded.

Neah Bay, WA, preserved specimen
Tonicella cf. venusta Clark, 1999
intertidal to 140m size to 1.7cm
northern Mexico to southern Alaska
This tiny species is rarely found intertidally. It has a light orange or pink background with white zigzag lines. Light dash markings along the center of the plates separate this species from the others. The girdle appears sandy. (The ID on the photo is not confirmed but it conforms to all characteristics.)

preserved specimen photographed intertidally

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.

Chitons (Polyplacophora)

Family Mopaliidae