Gastropods

Lepetidae

San Juan Islands, WA Petersburg, AK, encrusted extreme low tide, Oak Bay, WA

Lepeta concentrica (Middendorff, 1848)
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 - Cryptobranchia concentrica)

Acmaeidae

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]

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)

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)

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)

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)

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.

Lottiidae

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)

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 (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)

Siphonariidae

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.

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.

Trimusculidae

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)

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)

Family Acmaeidae, Lepetidae,

Lottiidae, Siphonariidae & Trimusculidae