Below you’ll see examples of intertidal green algae from exposed surf-swept shores of the Oregon coast. You are likely to encounter these greens on the rocks or in and around tide pools, and you’ll see some of them as drift on the beaches. Some of these are easy to identify with field guides and online resources (see References, below), others are tricky. I apologize for any misidentifications you may find. There’s nothing new here, just new looks at common greens, and a natural history note if I can think of something that hasn’t already been said. Since identification can be a challenge, I’ll show the tough ones too, the ones I can’t identify. Please drop me a line if you notice a misidentification or if you feel like helping me solve an identification mystery.

The organization more or less follows Kozloff (1993) and Lamb and Hanby (2005), showing species in the order they might be encountered in the field, from highest to lowest in the intertidal. Common names are my choice. I lean on WoRMS for scientific names, and Algaebase when I want to dig deeper. I learn a ton by browsing the pages of Kozloff (1993). All photos are from northern Oregon unless otherwise noted in the caption.

Ulva is a diverse group and pretty difficult for us casual beachcombers to say with much certainty what species we re looking at. Ulva has similarities to other greens and sometimes even landing on the right genus right is a leap of faith. The examples below are my leaps of faith.

Everybody says Ulva intestinalis is ubiquitous around high intertidal and splash zone seeps, so I’m guessing that’s what this is.

Below, Ulva carpets a high sand-scoured rock- I’m pretty sure it’s Ulva.

Leafy Ulva is common on the exposed coast, and really flourishes, with lush growth in semi-protected niches. I can’t speculate what species are represented below, but it’s reasonable to refer to the bladed forms as sea lettuce.

This Ulva looks a a lot like the one Kozloff and Oregon’s Rocky Intertidal call U. taeniata.

For a few other photos see Sea Lettuce, Ulva.


CladophoraSea moss is characteristic of the upper midlittoral, found with mussels, haystack barnacles, Fucus, and Endocladia.


Urospora? – This ID is tentative but you can’t really argue with the common name, green hair.


Spongy cushion, Codium setchellii Codium setchellii, a resident of the low intertidal, appeared in Spongy Cushion, Codium setchellii



Druehl, L. D. and B. E. Clarkston. 2016. Pacific Seaweeds: A Guide To Common Seaweeds of the Pacific Coast. 2nd ed. Harbour Publishing Co.

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.

Mondragon, J., and J. Mondragon. 2010. Seaweeds of the Pacific Coast. Shoreline Press.

Sept. J. D. 2009. The Beachcomber’s Guide to Seashore Life in the Pacific Northwest. Revised ed. Harbour Publishing.

Web Resources

The green algae page on the Netarts Bay Today website is one of the best references you’ll find for the Pacific Northwest.

Biodiversity of the Central Coast has a great page on greens.

Seaweeds of Alaska is a standard reference for the Pacific northwest. It has a great green algae page.

And, you can, and should, scroll down to the green algae section of Oregon’s Rocky Intertidal by Kate Krieg.


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