Snails

Below are a few examples of snails living on Oregon’s exposed rocky shores and, rarely, on the beaches. The photos are from northern Oregon unless noted. These are the easy-to-spot snails I’ve seen and photographed on the shores I’ve visited; they’re the ones you can find without turning rocks or creating disturbances. Organization-wise, I loosely follow Lamb and Hanby (2005). If I use common names, they’re my choice. Experts cover these examples and many more in the books, field guides, and identification resources listed at the bottom of the page.

Let the snails be upon you!


Nucella ostrina Northern striped dogwinkle

Nucella ostrina is most noticeable among the acorn barnacles Balanus glandula. They’re easy to find and, without question, one of the rocky intertidal snails I most enjoy.

Color and pattern variation in several individuals on a bed of acorn barnacles.
The color, pattern, and sculpturing of Nucella ostrina shells are variable
Two smooth-shelled N. ostrina, one orange and one pale.
A smooth orange shell is eye-catching
A few Nucella ostrina around a small patch of egg capsules.
Vase-shaped egg capsules
Four Nucella ostrina around a small mass of clean, pale new egg capsules.
Capsules contain a few embryos and lots of nurse eggs
Closeup of a pale-purplish shell with darker purple strips and some shell erosion, this one perched high up among the acorn barnacles.
Color, pattern, and sculpturing combine to make a lovely shell
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Nucella canaliculata Channeled dogwinkle

Close mid intertidal scene with six snails nestled in the corallines.
Nestled beautifully among the corallines
A mostly bare rock scene with three Nucella analoga (probably) and a rosette of young mussels.
I feel like those mussels are in danger
A little aggregation of Nucella analoga (probably) and Nucella ostrina. All the sails are pretty drab, but one of the N. analoga is bright orange.
An occasional burst of orange, Nucella style
Three Nucella species, some acorn barnacles, and a few small mussels share the top of a rock.
The not-too-uncommon but always delightful co-occurrence of three Nucella species
Shell coloration is usually muted or subdued; here, markedly drab


The shells’ ridges and the channels between them are a little variable and always captivating.

Three Nucella analoga (probably) on a background of barnacles.
A trio of dogwinkles on the central Oregon shore
A closeup of a lone snail on a background of barnacles.
Loner on a barnacle bed
In the foreground, several dogwinkles, in a stand of young Mytilus. Coastal slope in the background. Rain.
Among favored prey | Central Oregon


Dense aggregations occasionally materialize. The scenes below are from July.

Dense aggregation of dog winkles on a low rock surrounded by sand. Beach and some large protruding rocks in the background. Surf zone beyond. Cloudy sky.
Huddled on a low sand-scoured rock
Closeup on a dense aggregation of dogwinkles.
Quite a mob


Spring and early summer are favorable for finding clusters of flask-shaped egg capsules. Early development is completed inside the capsules and juveniles emerge as miniature snails.

A rock topped with dogwinkles, some egg masses clusters, and a starfish on one side. Surf size and beyond in the distance.
Piaster would like a word
Closeup on nine dogwinkles and a cluster of egg capsules on a bare rock (except for a crustose coralline in places).
An April laying
An assemblage of dogwinkles in and around a mass of egg capsules. Articulated corallines and giant green anemones are also present among the sand at the bottom of the scene.
An aggregation with egg capsules | June
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Nucella lamellosa Frilled dogwinkle

Nucella lamellosa shells tend to be brown, and dry eroded shells can be quite drab. Boldly banded shells and striking coloration aren’t particularly common on exposed Northern Oregon shores. Shell sculpturing, erosion, and degree of barnacle encrustation are variable.

Closeup of an aggregation of about 25 Nucella lamellosa Frilled dogwinkles on a mostly bare rock.
Closeup on four Nucella lamellosa Frilled dogwinkles hosting a few small dark limpets and variable numbers of encrusting barnacles.
Closeup of three Nucella lamellosa Frilled dogwinkles with shells hosting limpets and barnacles.
Closeup of three Nucella lamellosa Frilled dogwinkles on a bed of Plocamium.
Closeup of a single Nucella lamellosa Frilled dogwinkle on a bed of Anthopleura and Corallina.
Closeup of a single Nucella lamellosa Frilled dogwinkle. Anthopleura and coralline crust share the scene.


Spring is a good time to find masses of stalked, spindle-shaped egg capsules.

An intimate closeup of a single Nucella lamellosa Frilled dogwinkle nestled among masses of egg capsules.


Expect aggregations of snails around masses of their egg capsules.

A closeup of an aggregation of Nucella lamellosa Frilled dogwinkles around the edge of a mass of egg capsules.
A closeup of an aggregation of about a dozen Nucella lamellosa Frilled dogwinkles around and in a mass of egg capsules.


Small clusters of detached and drifted egg capsules are a common beachcombing find. Some people call the capsules sea oats.

Closeup of detached and drifted Nucella lamellosa Frilled dogwinkle egg cases resting on the sand.
Closeup of detached and drifted Nucella lamellosa Frilled dogwinkle egg cases resting on the sand.
Closeup of detached and drifted Nucella lamellosa Frilled dogwinkle egg cases resting on the sand.
Closeup of detached and drifted Nucella lamellosa Frilled dogwinkle egg cases resting on the sand.


On exposed northern Oregon shores, Nucella lamellosa leans toward lower zones than N. ostrina and N. canaliculata, but it’s not too uncommon to find them together. (Another example of all three Nucella species clustered together on a rock can be seen in the Nucella canaliculata entry, above.)

Closeup of an aggregation of three Nucella species: Nucella lamellosa Frilled dogwinkle, Nucella canaliculata Channeled dogwinkle, and Nucella ostrina Northern striped dogwinkle.
***


Littorina Periwinkles

Identifying periwinkles from photos like mine is tricky, but I’m pretty sure this entry includes a mix of checkered periwinkles Littorina scutulata and L. plena.

Backlit periwinkles Littorina atop a boulder.
Closeup on four periwinkles Littorina atop a wet boulder. A few blurry periwinkles in the background.
Closeup on four periwinkles Littorina clustered at a meeting of crevices on bare rock.
Closeup of a periwinkle Littorina on a mixed tuft or Fucus and Pyropia. Blurry barnacles scattered on a rock in the background.
Bringing the checkers to checkered periwinkle


Periwinkles are shy about showing off their tentacles, but they sometimes cooperate when the light is low and moisture high. Tiny and beautifully patterned, Littorina tentacles are something of a mystery because they’re usually withdrawn before you can get close enough for a peek or a photograph. They are a treat to behold when the opportunity presents itself, as they did in the image below.

Closeup on two periwinkles Littorina on a bed of seaweed, Pyropia, I think. Arrows indicate the tentacles.


A tale of checkered periwinkle tentacles

I devote time to tentacles because Sept (see references at the bottom of this page) and others have noted that tentacle pattern is one of the more reliable characteristics for checkered periwinkle identification. Incompletely-banded and speckled patterns are most associated with Littorina scutulata, while Littorina plena tentacles are adorned with an unbroken longitudinal stripe, sometimes with bands, or they can be uniformly dark. It’s been my good fortune to photograph a few checkered periwinkles with their tentacles extended. Below, I’ve organized a few examples in a pair of galleries for comparison.

Checkered periwinkles with incompletely-banded and speckled tentacles.

Closeup of a checkered periwinkle, probably Littorina scutulata, apparently feeding on Pyropia. Fucus, another Littorina, and barnacles in the background. Arrows point to tentacles.
Closeup of a checkered periwinkle, probably Littorina scutulata, on a bed of Fucus. An arrow points to a tentacle.
Closeup of a checkered periwinkle, probably Littorina scutulata, on a bed of Mazzaella parksii.
Closeup of the tentacles of a checkered periwinkle, probably Littorina scutulata, on a bed of Pelvetiopsis.
Closeup of a checkered periwinkle, probably Littorina scutulata, on a bed of Fucus.


For comparison, checkered periwinkles whose tentacles have an unbroken longitudinal stripe.

Closeup of a checkered periwinkle, probably Littorina plena, on a rock. Arrow points to a tentacle.
Closeup of a checkered periwinkle, probably Littorina plena, moving over sand. Arrow points to a tentacle.
Closeup of a checkered periwinkle, probably Littorina plena, moving over bare rock, both tentacles extended.
Closeup of four checkered periwinkle, probably Littorina plena, on a wet rock. Arrows point to tentacles on two of the snails. A few barnacles share the scene.
Closeup of a checkered periwinkle, probably Littorina plena, moving over barnacles. Bare rock in the background.


Leaving identification behind, here are some scenes from the life of Littorina. One of the things to notice about periwinkles is that they live together in close association.


Gatherings on seaweeds

Several periwinkles Littorina atop a tuft of Cladophora.
From the Central Oregon shore
Closeup on five periwinkles Littorina atop a tuft of a mixed tuft of Mazzaella parksii and Fucus.
Closeup on several periwinkles Littorina on a mat of Pyropia.


Biding time together in the crevices

Closeup featuring four periwinkles Littorina tucked in a crevice among barnacles doing the same.
Closeup featuring several periwinkles Littorina tucked in a crevice on mostly bare rock. A few tiny barnacles present.


Together on a bed of barnacles

Closeup featuring two periwinkles Littorina atop acorn barnacles near a crevice. Several other out-of-focus periwinkles on barnacles share the scene along with some bare rock.
Closeup featuring two periwinkles Littorina atop acorn barnacles. Several out-of-focus periwinkles on a bed of acorn barnacles share the scene.
Closeup featuring several periwinkles Littorina on a bed of acorn barnacles Balanus glandula.


Hitchhiking is a group activity

Closeup of a black turban with several hitchhiking periwinkles Littorina. A bunch more Littorina on a bed of seaweed in the foreground.
From the central Oregon shore


It wouldn’t be too big a surprise to find them out on the sand. They make mass movements at times. Notice that the snails in the scene below (except for a few caught messing around) are headed in the same direction.

Closeup featuring about 20 periwinkles Littorina moving in the same direction over the sand.


Travelling with purpose. In the pair of scenes below, from Oregon’s central coast, single file columns of Littorina are on the move. In the left-hand panel, the snails are moving away from their rock. In the right-hand panel, their movement is from the rock at the bottom of the frame to the rock at the top.

Columns of periwinkles Littorina apparently traveling away from their rock over the sand in the foreground.
Single file columns of Littorina travel over the sand from a rock in the foreground to another rock in the background.
Gastropodestrians


Periwinkles are well-known trail followers.

A pair of single file lines of periwinkles Littorina moving over the sand in the same direction.
Closeup on a single file line of periwinkles Littorina moving over the sand in the same direction.


Exodus

Periwinkles Littorina moving over the sand away from their rock.


Limpets will move along the same trails.

Seven periwinkles Littorina moving over the sand away from their rock are joined by two limpets, maybe Lottia pelta.
Two periwinkles Littorina moving over the sand are joined by a limpet, probably Lottia digitalis. (The limpet is in between the two periwinkles.)
***


Nassarius fossatus Channeled basket snail

Channeled nassas, as they are also known, apparently don’t overlap much with me in the northern Oregon intertidal. I don’t recall coming across a live one. Empty nassa shells, however, can be abundant, and hermit crabs frequently occupy them. Although I think the egg cases shown below are those of N. fossatus, I haven’t seen deposition, only drifted cases.

An empty shell up against a small piece of driftwood on small, wet gravel.
With natural polishing, empty Nassarius fossatus shells are beautiful | Central Oregon
About 30 drifted egg cases captured by a small anemone in a shallow, sand-filled pool.
Drifted egg cases are pretty common in pools and sea wrack | Central Oregon
Shell turned to reveal the opening, which is closed off by the pinching claw of the occupant, a hermit crab.
Hermit crabs prize empty Nassarius fossatus shells | Central Oregon
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Tegula funebralis Black turban

Black turbans are conspicuous and abundant. They seem more numerous on the central coast than in most northern Oregon locations.

The top of the shell is almost always eroded
A variety of small invertebrates hitch-hike on Tegula shells
Not much black at all here | Central Oregon
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Callianax biplicata Purple olive

On exposed beaches, up your odds of finding purple olives by walking out toward the swash on a pretty low tide. When things are just right, and I don’t know exactly what that looks like, they can be startlingly abundant. But you won’t find them on every stretch of the beach; maybe try a beach with large protruding boulders, stacks, or a contoured shoreline that gives a little shelter.

A lone snail on a journey over, and partially through, very wet (saturated) beach sand.
Callianax biplicata is at home on clean sandy beaches
Purple olive tracks in wet beach sand that resemble english letters G ad J
Purple olives have a lot to say, and they write it all down
A single snail emerging from its burrow. A strand of slime stretches from the burrow entrance to the snail (less than a cm).
Caught in the act of emerging
A single snail has left its burrow and is now moving over clean beach sand, barely leaving a trace.
Taking the surface route
Closeup, from above, on a single snail on clean wet sand.
Purple olives are lovely little snails


Below is a collection of traces left by purple olives. It’s worth knowing what you’re looking at so you don’t have to dig them up to find what made them.

Six dimples on clean sand. There's a purple olive beneath each one.
Shows
A trail in the sand that resembles the numeral six
Trail
A barely visible purple olive acting very much like a snowplow, plowing through wet sand.
Snowplow
A mounded tunnel created by a single olive burrowing just under the surface.
Tunnel
A dense collection of shows, plow tracks, and tunnels on clean wet sand.
Collection of traces


Onchidella Leather Limpet

Leather limpets blend in splendidly, making them easy to miss, and I don’t think I’m alone when I say that finding one, or several, tends to elicit a sense of gratitude and a genuine smile. Known for their stalked eyes, they’re pretty cute. (Below, the head is pointing down and you can see the eyes on their short stalks.)

Closeup of a solo leather limpet Onchidella carpenteri on a bed of acorn barnacles Balanus glandula in a mussel bed.


The image below, from atop an inaccessible rock, shows a scene bursting with high intertidal invertebrate life. (An interesting bit of information is that, as noted, I couldn’t access the top of the rock. To solve the problem and soothe my curiosity, I held my camera as high as I could and took the photo. As it turned out, there was a lot going on up there!) Can you pick out two leather limpets?

Two leather limpets Onchidella carpenteri in a scene of diverse high intertidal invertebrate life.

As far as I know, Pacific Northwest leather limpets are Onchidella carpenteri, but you may see some references to O. borealis.

References

Gotshall, D. W. 2005. Guide to Marine Invertebrates, Alaska to Baja California 2nd Edition (Revised). Shoreline Press.

Harbo, R. M. 2011. Whelks to Whales: Coastal Marine Life of the Pacific Northwest. 2nd ed. Harbour Publishing Co.

Kozloff, E. N. 1993. Seashore Life of the Northern Pacific Coast. 3rd ed. University of Washington Press.

Lamb, A. and B. P. Hanby. 2005. Marine Life of the Pacific Northwest. Harbour Publishing.

Sept. J. D. 2019. The New Beachcomber’s Guide to the Pacific Northwest. Harbour Publishing.


Online Resources

Friends of Netarts Bay WEBS Mollusks page. Accessed March 20, 2025.

It’s worth scrolling down to Gastropoda in Common Sea Life of Southeastern Alaska: A field guide by Aaron Baldwin & Paul Norwood. Accessed March 20, 2025.


Species Accounts

Bering, N., T. Hext and E. Parker. 2017. Nucella ostrina. In: Oregon Estuarine Invertebrates: Rudys’ Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. Accessed March 20, 2025.

Charbonneau, N., Helmstetler, H., and Cowles, D. (2009). Nucella ostrina (Deshayes, 1839). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed March 20, 2025.

Cowles, D. (2004). Chlorostoma funebralis (A. Adams, 1855). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed March 20, 2025.

Cowles, D. (2004). Littorina scutulata Gould, 1849. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed March 20, 2025.

Cowles, D. (2005). Nucella canaliculata (Duclos, 1832). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed March 20, 2025.

Cowles, D. (2006). Nassarius fossatus (Gould, 1850). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed March 20, 2025.

Cowles, D. (2006). Callianax biplicata (Sowerby, 1825). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed October 7, 2025.

Cowles, D. (2007). Onchidella borealis Dall, 1871. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed March 20, 2025.

Valley, J. and T.C. Hiebert. 2015a. Littorina plena. In: Oregon Estuarine Invertebrates: Rudys’ Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. Accessed March 20, 2025.

Valley, J. and T.C. Hiebert. 2015b. Littorina scutulata. In: Oregon Estuarine Invertebrates: Rudys’ Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. Accessed March 20, 2025.


I updated this page on March 20, 2025.