Below are examples of intertidal greens, mostly from the surf-swept shores of the northern Oregon coast (unless otherwise noted in the captions). Some greens are tricky, even for experts, and I’m not an expert. I’m happy with genus-level identifications, when I can get there. Please drop me a line if you see a mistake or feel like helping me fill a gap. I made this page to organize my own thoughts about greens, and along the way, share different looks at the common ones and their habitats.

My organization loosely 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. I lean on Algaebase for nomenclature and taxonomy. Common names are my choice. I learn a ton by browsing the pages of Druehl and Clarkston (2016) and Kozloff (1993). You’ll find a bunch more easy to find references at the bottom of the page.

Ulva intestinalis

In the right setting, frequently at freshwater seeps, U. intestinalis can creep to the highest reaches of the splash zone, above the highest barnacles and limpets. All of the images below are from the splash zone seeps, so I’m guessing they’re all U. intestinalis. But, it’s not restricted to seeps.


Cladophora, Sea moss

Cladophora is frequently found with periwinkles, mussels, thatched barnacles, Fucus, and Endocladia.


Sea lettuce

Leafy, bladed Ulva is common on the exposed coast, and flourishes, with lush growth, in semi-protected niches. I won’t speculate what species are represented below.


Ulva taeniata, sea spiral

Sea spiral is a distinctive bladed Ulva. I don’t notice it too much, but my impression is it’s at home in and around sand-fill tidepools.



These emerald plaits are probably those of A. coralita, green rope.


Codium, Spongy cushion

Codium is always intriguing. I think all the examples below are C. 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.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s