Below are examples of intertidal greens from the surf-swept shores of the northern Oregon coast (unless otherwise noted in the captions). Some greens seaweeds 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. This page organizes my thoughts about greens and shares my take on 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.
Let’s explore some green seaweeds!
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. It’s also found in high tidepools.
The filaments below, known for their large barrel-shaped cells, are probably Urospora. I’ve highlighted the large cells in the lower right panel below.
Cladophora, sea moss
Cladophora is frequently found with periwinkles, mussels, thatched barnacles, Fucus, and Endocladia.
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. It’s at home in and around sand-filled tidepools.
Acrosiphonia coalita, green rope
Codium fragile, sea staghorn
Codium setchellii, spongy cushion
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.
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.
This page was updated on July 3, 2021.