Although the following species look like limpets, they are not closely related to the species above.

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

Cryptobranchia concentrica Cryptobranchia concentrica Cryptobranchia concentrica
           San Juan Islands, WA                              Petersburg, AK, encrusted                                       extreme low tide, Oak Bay, WA
Cryptobranchia concentrica (Middendorff, 1847)
Ringed Blind Limpet
intertidal to 60m          central California to northern Alaska          size to 23mm
This is infrequently found intertidally.  It is a white shell with a low profile and may be encrusted, obscuring its color.  There is another small white
limpet, Lepeta caeca, also rarely seen, which has small pustules on its shell which can distinquish it from this species.
(previous name - Lepeta concentrica)

Acmaea mitra Acmaea mitra Acmaea mitra
  all specimens from area of Whiskey Creek Beach, WA    intertidal                                               subtidal
Acmaea mitra Rathke, 1833
Whitecap Limpet *
intertidal to 60m          northern Mexico to northern Alaska          size to 50mm
 This is commonly found intertidally.  Its tall conical profile is unmistakeable.  The shell is white but it is frequently encrusted with white or red coralline algae.  [all specimens shown are from Whiskey Creek Beach, WA]


Family Acmaeidae, Lepetidae, 

Lottiidae, Siphonariidae & Trimusculidae

Lottia asmi Lottia asmi
                                     Monterey Bay, CA                                                               Cape Arago, OR, intertidal

Lottia fenestrata Lottia fenestrata
         Yachats, OR                                 Whiskey Creek Beach, WA, intertidal
Lottia fenestrata (Reeve, 1855)
Fenestrate Limpet or Chocolate Limpet
intertidal          northern Mexico to Alaska          size to 26mm
This species is infrequently found.  It lives in the lower intertidal zone and is usually found at the base of rocks burrowed into the sand at low tide.    The top of the shell is usually eroded and it can be difficult to identify without seeing the interior of the shell.  The interior may be a solid dark chocolate brown to a lighter brown with only a dark lower ring.  The apex is slightly off center.
(previous names - Tectura fenestrata, Notoacmaea fenestrata, Collisella fenestrata, Acmaea fenestrata, Acmaea cribraria)

Lottia digitalis Lottia digitalis
                                           all Deception Pass, WA            intertidal
Lottia digitalis (Rathke, 1833)
Ribbed Limpet or Finger Limpet *
high intertidal          northern Mexico to northern Alaska          size to 35mm
This is commonly found in the higher intertidal zone.  It lives among the barnacles.  The apex is far forward
on the shell and it has distinct ridges.  It is generally patterned with brown markings and spots.  This species
is hard to confuse with any other in our area.
(previous names - Collisella digitalis, Acmaea digitalis, Collisella austrodigitalis, Acmaea radiata)

Lottia instabilis Lottia instabilis Lottia instabilis Lottia instabilis
 Whiskey Creek Beach, WA                            Slip Point, WA, intertidal                                            Port Angeles, WA, subtidal   Freshwater Bay, WA, subtidal    
    kelp morph                                                        kelp morph                                                             kelp morph                           rock morph        
Lottia instabilis (Gould, 1846)
Unstable Limpet *
intertidal to 73m          southern California to northern Alaska          size to 35mm
This species is generally easy to find, although it is usually as a dead shell washed ashore.  The most recognizeable form of this species has a distinct oval shape and high profile.  It lives on the stipes of kelp and is frequently encrusted with coralline algae.  This species also has an ecomorph which
 lives on rocks or shells.  The rock morph is difficult to separate from the other common intertidal species as it exhibits similar patterned markings and profile, although it has parallel sides.  The rock morph used to be described under the name Lottia ochracea.
(previous names - Notoacmaea instabilis, Collisella instabilis, Acmaea instabilis)

Lottia asmi (Middendorff, 1847)
Black Limpet
intertidal          size to 10mm
 northern Mexico to southern Alaska
This species is hard to find.  It generally lives on the shell of the Black Turban, Tegula funebralis.  The color of the limpet blends with the color of turban shell.
(previous names - Collisella asmi, Acmaea asmi)



Lottia pelta Lottia pelta Lottia pelta
           Petersburg, AK                       Marrowstone Is., WA                   Whiskey Creek Beach, WA, feeding trail

Lottia persona Lottia persona
         left - Petersburg, AK, right - Yachats, OR                              Waldron Island, WA, intertidal
Lottia persona (Rathke, 1833)
Mask Limpet *
high intertidal          northern Mexico to northern Alaska          size to 50mm
This is a very commonly found species.  It lives in the very high intertidal zone.  The interior may be white to
 bluish with a dark band at the base.  The exterior may have varying amounts of patterning.  Juveniles often
show faint radial ribs, but these become obscured on older specimens.  The shell also becomes significantly
higher as it ages.  These shells are rarely obscured by algae or other overgrowth.  As with many limpets,
 their shape, height and coloration may be affected by their habitat.
(previous names - Tectura persona, Notoacmaea persona, Acmaea persona, Collisella radiata)

Lottia aff. rosacea Lottia aff. rosacea Lottia aff. rosacea
                        Bremerton, WA                                                             Anacortes, WA                                                         Point Bolin, WA, intertidal
Lottia aff. rosacea (Carpenter, 1864)
Pacific Rosy Limpet
low intertidal to subtidal?          California to BC?          size to 8mm
This species is occasionally seen.  Preliminary studies show this species may not be the same as Lottia rosacea, which is
described from specimens in California.   Even within California, this name may represent a group of similar species.
Locally our specimens have light brown to pinkish markings, a round to oval shape and slightly off center apex.  

Lottia triangularis
Barkley Sound, BC

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Discurria insessa Discurria insessa
                                 Monterey, CA                                                                          Monterey, CA,  intertidal
Discurria insessa (Hinds, 1842)
Seaweed Limpet
intertidal          northern Mexico to southern Alaska          size to 22mm
This species is hard to find.  It feeds on the feather boa kelp but is very difficult to spot.  It has a relatively smooth brown surface and is difficult to confuse with any other species.
(previous names - Notoacmaea insessa, Collisella insessa, Acmaea insessa, Patella insessa)

Lottia limatula
Long Beach, CA
Lottia scutum Lottia scutum Lottia scutum
left-Petersburg, AK; center-Slip Point, WA;                           Marrowstone Island, WA, intertidal                Slip Point, WA, note the brown tentacles
             right-Deception Pass, WA
Lottia scutum (Rathke, 1833)
Pacific Plate Limpet *
intertidal to shallow subtidal          northern Mexico to northern Alaska; Japan; Siberia          size to 64mm
This is a very common species.  It is very similar in appearance to L. pelta but usually a little lower in the intertidal.  This shell has a rather brittle outer edge.  The tentacles of the animal are brown which also distinguish it from our other limpets whose tentacles match the
animals' body color.  It is typically low in height but may grow quite large and high in some habitats.  The shell surface is often covered in algaes or seaweeds.
(previous names - Tectura scutum, Notoacmaea scutum, Acmaea scutum, Acmaea testudinalis scutum)

Lottia limatula (Carpenter, 1864)
File Limpet
intertidal          northern Mexico to southern BC         size to 50mm
This species is rare to find in the Pacific Northwest.  North of central Oregon, it has only been found around southern Vancouver Island in BC.  The scales along the ribs are its identifying feature, although the scales can be worn nearly smooth.  It prefer the outer coast or high current areas.
 [see article on finds in BC]
(previous names - Collisella limatula, Acmaea limatula)

Lottia pelta Lottia pelta
 Boundary Bay, BC                       Birch Bay, WA, intertidal
(This eelgrass form previously known as Lottia parallela.)

Lottia pelta (Rathke, 1833)
Shield Limpet *
intertidal          northern Mexico to northern Alaska;  Siberia          size to 54mm
This is a very common species and is one of our most abundant limpets.  It has a highly variable shape and coloration depending on its habitat.  It generally has a high apex, slightly forward on the shell.  The shell is normally narrower toward the front.  When not highly eroded by waves or encrustations, it exhibits radial ribbing.  The color may be light to dark with radial banding.  The shell is frequently covered by
algae or encrustions.  This species may have several ecomorphs.  Preliminary
studies have shown that the Pacific Eelgrass Limpet, Lottia parallela, is simply an ecomorph of Lottia pelta.

(previous names - Collisella pelta, Acmaea pelta, Acmaea cassis, Acmaea olympica, Acmaea nacelloides)

Siphonaria thersites Siphonaria thersites Siphonaria thersites
                                      Haida Gwaii, BC                                                             Neah Bay, WA                                 Neah Bay, WA
Siphonaria thersites (Carpenter, 1864)
Carpenter's False Limpet
high intertidal          north Washington to Alaska to Russia          size to 10mm
This is actually an air-breathing land species. It lives on rocks and seaweed close
to the high tide level and can sometimes be found dead on the beach. We include it here because it is easily mistaken for a marine limpet, although it is uncommon to find.  Seems to prefer beaches with some protection on the open coast.

Lottia scabra Lottia scabra Lottia scabra
               Bodega Harbor, CA                                                                     Cape Arago, OR, intertidal
Lottia scabra (Gould, 1846)
Rough Limpet
intertidal          north Mexico to Cape Arago, OR          size to 35mm
This limpet is found only at the very southern portion of the "Pacific Northwest".  It lives in the upper mid-intertidal to the high intertidal and prefers a horizontal surface.  Its prominent ribs form a scalloped margin to the shell.  This species returns to a "home spot" on the rock at low tide.  In the right photo, the home depression is visible in the easily worn sandstone. 
(previous names - Collisella scabra, Macclintockia scabra, Acmaea scabra)

Lottia triangularis (Carpenter, 1864)
Triangular Limpet
low intertidal to subtidal          California to BC?          size to 8mm
This species is rarely seen.  There are two forms.  The elongated
form is shown here and it is often
white and encrusted with coralline algae.  A more compressed, wider form lives on the stipes of
 corallines and exhibits more markings.

Trimusculus reticulatus Trimusculus reticulatus
                Coos Bay, OR                                      Coos Bay, OR, intertidal in cave, with eggs
Trimusculus reticulatus (Sowerby, 1835)
Reticulate Button Snail
very high intertidal          Chile; northern Mexico to northern Washington          size to 20mm
This species is very rare to find.  It lives in crevasses and caves.
This is an air breather, spending most of its time out of the water.
(previous name - Gadinia reticulata)  

Acmaea funiculata Acmaea funiculata
                                       Carmel Bay, CA                                                             off San Pedro, CA, subtidal
Acmaea funiculata (Carpenter, 1864)
Corded White Limpet
subtidal, 15-70m          north Mexico to central Alaska          size to 25mm
This species is generally only seen by divers.  Often it is heavily encrusted by other organisms and hard to spot.  A dead shell might easily be confused with some of our keyhole limpets with similar corded exteriors.  The lack of a hole near the apex would identify this species.   The interior may be pink in color when it's been feeding on coralline algae.
(synonym - Niveotectura funiculata)


This page last revised: 12-18-2021