Greens, Chlorophyta

Below are examples of intertidal greens from the surf-swept shores of the northern Oregon coast. A fair number of the green seaweeds pose identification challenges (for me!), so I’m happy with genus-level identifications when I can get there. Please drop me a line if you see a mistake. My organization loosely follows Kozloff (1993) and Lamb and Hanby (2005), showing species you might encounter in the field, from highest to lowest in the intertidal.

I turn to 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 more references at the bottom of this page.

Let’s explore some green seaweeds!

Ulva intestinalis
In the right setting, frequently at freshwater seeps, U. intestinalis can creep to the highest reaches of the splash zone and above. You can also find it in high tidepools.

Ulva can creep higher than the highest acorn barnacles — *Ulva intestinalis* creeping up a rock wall at a seep

Medium closeup on exposed tubes at a seep on a wall — *Ulva intestinalis* creeping up a rock wall at a seep

Cladophora
Discovering lush tufts of Cladophora is a high (and sometimes mid) intertidal pleasure.

Foreground a high rock covered in intertidal life (mussels, barnacles, other red and green seaweeds; the view is out across the beach to the surf zone. — *Cladophora* in a diverse intertidal community

closeup of moss-like tufts among acorn barnacles in the high intertidal — *Cladophora* in a diverse intertidal community

The unbranched filaments below have large cells visible to the unaided eye if you’re looking. All of the images in the set below are from semi-protected mid-intertidal settings with lots of sand. So, with habitat and cell size in mind, one of the possibilities is Chaetomorpha. (There here are other contenders, though.)

A tide pool with strands hanging down and draped over an exposed rock — Semi-protected site | Central Oregon

A sand-filled tidepool with strands draped over a rock and into the shallow water of the pool — Semi-protected site | Central Oregon

You’ll see Ulva on the exposed coast sooner rather than later. Lush growth can occur under the right conditions, and Ulva‘s diversity is enough to keep you interested (and you may have a few other feelings too) for the rest of your life.

Sunrise on the Ulva rock garden (foreground); beyond tidepoos and large rocks jutting skyward; beyond that the open see and a lightly colored horizon — *Ulva* garden | Central Oregon

A dense carpet of Ulva interspersed with Fucus on a rocky Mayne Island shore. — *Ulva* garden | Central Oregon

This is one of those holey ones with broad, fan-shaped blades, maybe something like Ulva fenestrata. You sure wouldn’t be out of line calling it sea lettuce.

An attached tuft of Ulva in a shallow, sand-filled pool. Blades are narrow at the base, but quick broaden with lots of holes. The Ulva is framed between two clumps of Corallina.

Ulva taeniata is pretty distinctive. It’s at home in and around sand-filled tidepools, and its common name, sea spiral, makes sense.

A fairly close up view on one strand over sand in a shallow tidepool — A lovely strand of sea spiral, *Ulva taeniata* | Central Oregon

One Ulva laid atop another — A lovely strand of sea spiral, *Ulva taeniata* | Central Oregon

Long ruffled blades suggest Ulva linza. The examples below are from the edge of a semi-protected boulder field with plenty of sand.

Bright ruffled blades hang down the side of a boulder in a shallow sand-filled pool. Beach in the mid ground, forest behind. Cloudy skies — Bright and ruffled

Long slender blades laying out on wet sand. — Bright and ruffled

Acrosiphonia coalita, green rope

Acrosiphonia sharing small rock with Ulva — *Acrosiphonia coalita* lives up to its common name | Central Oregon

Looking down on a flat-topped rock covered by Acrosiphonia and Ulva. — *Acrosiphonia coalita* lives up to its common name | Central Oregon

Codium fragile, sea staghorn

Close up look at a little clump — Nothing on this shore resembles *Codium fragile* | Central Oregon

Codium setchellii, spongy cushion

Close up view of a single patch of Codium — *Codium setchellii* sharing the stage with *Dilsea*

Codium among articulated corallines — *Codium setchellii* sharing the stage with *Dilsea*

References

Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford, Calif. Stanford University Press.

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.

This page was updated on June 4, 2022.

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