Sea Anemones

Below are examples of anemones I’ve seen living on Oregon’s exposed rocky intertidal. Compared to what you could find, it’s a limited sample, just the most obvious common forms I’ve been lucky enough to find and photograph on the shores I visit without committing too much disturbance. The photos are from northern Oregon unless noted. Organization-wise, I follow Lamb and Hanby (2005). If I use common names, they’re my choice. Experts cover the anemones shown below and many more in the books, field guides, and identification resources listed at the bottom of the page.

Let there be anemones!


Metridium senile Short plumose anemone

Underwater, with its tentacles extended, it’s a beautiful anemone. Unfortunately, I’ve only rarely experienced that beauty on exposed Oregon shores I’ve visited. The few times I have discovered them on the exposed coast, the places where they established themselves (e.g., the protected backsides of vertical walls or boulders in surf-swept settings) were inaccessible except at the lowest tides. Colonies can unexpectedly vanish without a trace.

A profusion of short plumose anemones Metridium senile exposed by low tide. A large Pisaster, giant green anemones, and aggregating anemones are also present.


Metridium senile can reproduce quickly through budding which might explain the multiple size classes seen in these images.

Multiple size classes of short plumose anemones Metridium senile exposed by low tide. The larger individuals are drooping down.
Multiple size classes of short plumose anemones Metridium senile exposed by low tide. A few pink-tipped green anemones share the scene.
Multiple size classes of retracted short plumose anemones Metridium senile exposed by low tide.


Exposed by low tides, Metridium senile can retract not only its tentacles, but its body column too.

Closeup on three highly retracted short plumose anemones Metridium senile exposed by low tide. Barnacles share the scene.


On the backside of a large surf-swept rock, the vertical wall shown below briefly hosted a mix of orange and gray Metridium senile.

A rock wall populated by multiple size classes of retracted short plumose anemones Metridium senile exposed by low tide. Both orange and gray color forms are present.
Multiple size classes of retracted short plumose anemones Metridium senile, the orange form, exposed by low tide.
Closeup on a dozen or so highly retracted orange short plumose anemones Metridium senile exposed by low tide. A couple lined chitons share the scene.
Multiple size classes of retracted short plumose anemones Metridium senile, the gray form, exposed by low tide.
***


Urticina grebelnyi Painted anemone

I think the anemones shown in the set below, all from protected niches on the exposed southern Oregon shore, are painteds. However, I can’t claim much experience with Urticina nor much in the way of anemone identification skills, so there is uncertainty. Either way, this good-sized anemone is a low intertidal beauty. Their color and pattern variation is striking.

An olive green painted anemone Urticina grebelnyi with just a few red streaks hangs down beneath a ledge.
Early sun shines on a painted anemone Urticina grebelnyi (with mottled red streaks) hanging down under a ledge.
Early sun shines on a painted anemone Urticina grebelnyi (Mostly red with some olive on the oral end) hanging down under a ledge.
A painted anemone Urticina grebelnyi (probably) hanging down, tentacles retracted. The column is coppery olive-green with faint traces of red.

Painteds, at least those I’ve encountered, are very much at home attached to vertical walls and overhangs. On these perches, exposed by low tides, and remember, these are large anemones, hanging down is just the way it is going to be. Of this, Kozloff says “…the way it hangs down limply when the tide is out is fascinatingly obscene.”

A painted anemone Urticina grebelnyi (with mottled red streaks) hanging down with semi-retracted tentacles.
A painted anemone Urticina grebelnyi (red with olive flecks) rests, mostly retracted, under a ledge. Ostrich plume hydroids Aglaophenia share the edges of the scene.
A painted anemone Urticina grebelnyi (with mottled red streaks) hanging down with tentacles retracted and stomach (or something like it) slightly protruding through the oral opening.
***


Anthopleura xanthogrammica Giant green anemone

Giant greens have been honored with one of the all-time best scientific names and with their accessibility, size, and beauty, they are tidepool superstars.

Medium close up, about six decent-sized giant green anemones Anthopleura xanthogrammica fill the frame.


In a still pool, giant greens are a never-ending source of wonder.

A giant green anemone Anthopleura xanthogrammica, in a shallow pool.


From beyond the tidepools

Giant green anemones Anthopleura xanthogrammica clinging to an overhanging rock wall. Low to mid- intertidal scene in the distance.
A giant green anemone Anthopleura xanthogrammica and a couple pisaster in a shallow, sandy surge channel.
Giant green anemones Anthopleura xanthogrammica cascade down a rock wall. A few red blades are also in the scene.
An intimate view of a giant green anemone Anthopleura xanthogrammica hanging down a vertical rock wall. Portions of two other giant greens and some Anthopleura elegantissima also appear in the scene.
A giant green anemone Anthopleura xanthogrammica on a vertical rock wall. Apparently, it became detached, dropped down a few inches (possibly onto the sand), then reattached.
???


The Daily Catch

A large giant green anemone Anthopleura xanthogrammica bulging with a cluster of detached California mussels it somehow managed to secure.
Closeup of a giant green anemone Anthopleura xanthogrammica with a single California mussel shell (both valves).
Closeup of a giant green anemone Anthopleura xanthogrammica with a porcelain crab pinching claw.
An exposed giant green anemone Anthopleura xanthogrammica with a Dungeness crab walking leg, pinching claw, and part of the body.
***

Anthopleura elegantissima

This anemone carries around a lot of common names, the most familiar of which, at least to me, are aggregating and pink-tipped green. They’re beauties in and out of the tidepools and you don’t have to wait for a super low tide to find them. Instead, they’re abundant in mid-intertidal pools and on the rocks.

Pink-tipped green anemones Anthopleura elegantissima on the edge of a sand-filled tide pool. A large Pisaster and a few large giant green anemones are also present.


When it comes to intertidal beauty, Anthopleura elegantissima delivers.

Closeup on a lineup of three pink-tipped green anemones Anthopleura elegantissima, tentacles extended, in a clear, shallow tidepool.


When you encounter Anthopleura elegantissima there’s likely to be a crowd.

Scores of tightly packed pink-tipped green anemones Anthopleura elegantissima on a rock wall exposed by low tide.
About 30 tightly packed pink-tipped green anemones Anthopleura elegantissima on the edge of a shallow sand-filled pool.
Closeup on about six tightly packed pink-tipped green anemones Anthopleura elegantissima in a shallow pool.


Be on the lookout for thin bands of open ground between aggregations.

A scene of tightly packed pink-tipped green anemones Anthopleura elegantissima ion a rock exposed by low tide. A thin band of space between two adjacent aggregations is featured. A few giant green anemones and a large Pisaster share the scene.
Tightly packed pink-tipped green anemones Anthopleura elegantissima on a rock exposed by low tide. Thin bands of open ground appear between adjacent aggregations. Scattered barnacles share the scene.
Tightly packed pink-tipped green anemones Anthopleura elegantissima on a rock exposed by low tide. Thin bands of open ground appear between adjacent aggregations. Barnacles and a few baby mussels share the scene.
***


Anthopleura artemisia, moonglow anemone 
On the exposed outer coast, you’ll almost always find moonglows where sand meets rock.

Anthopleura artemisia extending its tentacles from a hole in a clear tidepool.
Peeking out from cover
Anthopleura artemisia in a shallow, sand-filled tidepool.
The tentacles frequently have white bands
Anthopleura artemisia extending its orange tentacles from the sand in a shallow, clear pool.
There is quite a bit of color variation
Closeup on a lone moonglow anemone, greenish and a bit luminescent.
Monnglows are a bit luminescent | Galiano Island
***

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 Sea Anemonies, Hydroides, Jellies (Phylum Cnideria) and Comb Jellies (Phylum Ctenophora) page. Accessed January 8, 2026.

It’s worth scrolling down to anemones in Common Sea Life of Southeastern Alaska: A field guide by Aaron Baldwin & Paul Norwood. Accessed January 8, 2026.

Species Accounts

Cowles, D. (2004, as edited). Anthopleura artemisia (Pickering in Dana, 1848). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed January 8, 2026.

Cowles, D. (2005, as edited). Metridium senile subsp. fimbriatum (Verrill, 1865) [Harbo, 1999 says Linnaeus, 1767]. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed January 8, 2026.

Cowles, D. (2005). Urticina crassicornis (O. F. Muller, 1776). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed January 8, 2026.

Piazzola, C.D. and T.C. Hiebert. 2015. Metridium senile. 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 January 8, 2026.

Piazzola, C.D. and T.C. Hiebert. 2015. Anthopleura artemisia. 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 January 8, 2026.

White, B. (2002 as edited). Anthopleura xanthogrammica, Brandt (1835). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed January 8, 2026.

White, B. (2002 as edited). Anthopleura elegantissima (Brandt, 1835). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed January 8, 2026.


I updated this page January 9, 2026