Chitons (Polyplacophora)

Family  Chaetopleuridae & Ischnochitonidae

Chaetopleura gemma Dall, 1879
Gem Chiton
intertidal          northern Mexico to southern BC          size to 2cm
This is a very small species and rarely found in the Northwest.  It has a dark spot on the posterior valve which is distinctive for the species.
(synonym - Ischnochiton marmoratus)

Lepidozona radians Lepidozona radians Lepidozona radians 
             preserved specimens                                                               photographed intertidally                       

Lepidozona cooperi (Dall, 1919) Lepidozona cooperi
          preserved specimen                                photographed intertidally
Lepidozona cooperi (Dall, 1919)
Cooper's Chiton
intertidal to 20m          northern Mexico to northern BC          size to 5cm
It is infrequently found intertidally to the north.  This is similar to the Merten's Chiton but with strong shell sculpturing and smaller girdle granules.  It is usually grayish in color. It seems to be primarily an outer coast species and not found in interior waters.
(previous name - Ischnochiton cooperi)

Lepidozona interstincta
photographed subtidally
Lepidozona interstincta (Gould, 1852)
Smooth Lepidozona
very low intertidal to 70m          size to 3cm
Washington to north Alaska
 This is a small species which lacks obvious sculpturing on its plates.  The color is tan or more commonly, rusty red.  It is virtually identical to L. radians, but has a smaller range and deeper habitat.  They can also be distinguished via DNA.
(previous name - Ischnochiton interstinctus)
Lepidozona radians Lepidozona radians
uncommon turquoise and albino color - intertidal


Lepidozona mertensii
good example of its sculpture detail

Lepidozona mertensii (Middendorff, 1847)
Merten's Chiton *
intertidal to 91m          northern Mexico to northern Alaska; Japan         size to 5cm
This is a common intertidal species. The girdle is very granular in appearance and usually banded.  It is usually red with creamy white and is variably patterened.  The plates can run the extreme from all red to all white.

Lepidozona willetti
preserved specimen
Lepidozona willetti Berry, 1917
Willett's Lepidozona
subtidal          size to 3cm
southern California to southern Alaska
It is very similar to Lepidozona retiporosa and
often found near that species.  This species is
usually orangish to reddish-brown.
(previous name - Ischnochiton willetti)

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Lepidozona retiporosa Lepidozona retiporosa
          preserved specimen                            found subtidally
Lepidozona retiporosa (Carpenter, 1864)
Little Lepidozona
subtidal to 1000m         size to 2cm
northern Mexico to southern Alaska
It is often found near Lepidozona willetti.

This page last revised: 8-18-2020 
Lepidozona mertensii Lepidozona mertensii Lepidozona mertensii 
all photographed intertidally

Lepidozona radians (Carpenter, 1892)
intertidal to at least 13m          size to 2.5cm
northern Mexico to southeastern Alaska
This is infrequently found intertidally.  It is virtually identical to L. interstincta, but this species is found at shallower depths and over a wider geographic range.  It is also variably colored and patterned.
(previous name - Ischnochiton radians)  

Tripoplax trifida Tripoplax trifida
found subtidally

Tripoplax trifida (Carpenter, 1864)
Three-Rib Chiton
intertidal to 110m          size to 6cm
Puget Sound, WA to northern Alaska
This is rare to find intertidally.  It is usually reddish and sometimes patterned.  It has three low, flat ribs on the lateral areas of the central valves.
(previous names - Ischnochiton trifidus, Lepidozona trifida)

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