Below you’ll see examples of common intertidal brown seaweeds, mostly from exposed surf-swept shores of the northern Oregon coast. These are seaweeds you are likely to encounter on the rocks, or as drift on the beaches. Some are common and easy to identify with readily available guides (you’ll see a few in References, below). Others are tricky. I try to get the IDs right, but I’m far from an expert. I apologize for any misidentifications, if you see something amiss, please let me know. There’s nothing really new here, just my photos of common browns, and a natural history note if I can think of something that hasn’t been said or seems over- or underemphasized. I’ll show some browns I can’t identify too. Please drop me a line if you can resolve a mystery.

My organization more or less follows Kozloff (1993) and Lamb and Hanby (2005), showing species in the order they might be encountered in the wild, from highest to lowest in the rocky intertidal. Common names are my choice. I go to Algaebase for scientific names and other juicy information, and I learn a ton from the pages of Druehl and Clarkston (2016) and Kozloff (1993). All photos are from northern Oregon unless noted in the caption.

Let’s explore some browns!

Fucus, rockweed

Fucus seems to grow most luxuriantly in sheltered or semi-sheltered places. On surf-swept rocks it’s smaller than at protected sites, and frequently interspersed with Cladophora, Endocladia, and Pelvetiopsis. Drifted Fucus shows up commonly on the beaches. I’m guessing all the images below show Fucus distichus.


Pelvetiopsis limitata, little rockweed

P. limitata is at home only on the exposed outer coast, where it can be abundant on the tops of high intertidal rocks. I don’t often find drift Pelvetiopsis on the beaches.


Melanosiphon intestinalis, dark sea tubes

Also called twisted soda straws, look for it in winter and early spring.


Leathesia marina, sea cauliflower

There are some similar saclike epiphytic browns, but I think this one is Leathesia marina. Sea cauliflower can attach to rocks or live as an epiphyte.


Soranthera ulvoidea, studded sea balloon

Soranthea is an epiphyte on Neorhodomela and Odonthalia. It’s not uncommon to find Soranthera on the beach, attached to its drifted host.



Fir Branch, Analipus japonicus-  I’ve also seen A. japonicus referred to as bottle brush. My sketch looks more like a bottle brush, so I’ve got to mention it. The images shown here are from the central Oregon coast. I’ve never noticed it on my home beaches in northern Oregon. Look for it in the mid- to low intertidal


Postelsia palmaeformis, sea palm

It’s a treat to see stubby sea palms bobbing and poking through wicked surf, They live out on exposed headlands where reaching them is tricky, even at the lowest tides. Detached clumps are fairly common as sea wrack.


Hedophyllum sessile, Sea Cabbage,

The accepted scientific name has bounced around a bit. You may see it as Saccharina sessilis. Depending on the age of the blades and wave exposure, it’ll give you different looks. It’s one of the few kelps with no stipe, so that should help with identification. I don’t see much sea cabbage in the drift line.


Feather Boa Kelp, Egregia menziesii – Feather boa is common on mid to low intertidal rocks, and not unusual in the drift line. It’s a photo-friendly brown, giving lots of good looks.


Winged kelp, Alariamarginata –  In exposed places with low rocks and active sand, it experiences seasonal burial. In some of the photos below you can see the “wings” near the base of the stipe. Alaria marginata appears in Seaweeds in the Sand.


Split kelp, Laminaria setchellii – Laminaria setchellii appeared in Seaweeds in the Sand because in some places, it experiences seasonal burial. It’s also featured in Kelp Curves because it’s just so dang photogenic.


Laminaria sinclairii, dense-clumped kelp

In northern Oregon, Laminaria sinclairii‘s a good marker for mean lower low water.


Lessoniopsis littoralis

You know you’re on the exposed outer coast when you run into Lessoniopsis littoralis. It also goes by northern tree kelp, for its tree-like look; and strap kelp, for its strap-like blades.


Bladder chain, Stephanocystis osmundacea- My home beaches are a bit north of bladder chain strongholds. I only know it from the drift line.


Wireweed, Sargassum muticum

Not really at home in exposed surf-swept settings, it can be dense in protected waters and semi-protected pools. Drifted Sargassum is common on beaches.


Acid weed, Desmarestia – You can find this Desmarestia in low tide pools. It seems to tolerate active sand and sesonal sand burial.


Giant kelp, Macrocystis pyrifera – On my home beaches Macrocystis is subtidal, so I only know it from drift masses on the beach. Macrocystis drift is common enough that it appeared in my post, Common Marine Algae in the Northern Oregon Drift Line: A Gallery of ImagesMacrocystis is featured on the Monterey Bay Aquarium Logo.


Bull kelp, Nereocystis luetkeana – Bull kelp is subtidal, but in the wrack, it’s an important component of intertidal ecosystems. I wrote a little bit about this in Bull Kelp Drift: A Subtidal-to-Surf Zone Connection.


Pterygophora californica – Old growth kelp is mostly subtidal in Oregon, though you may run across it on the lowest tides. I don’t see it often, even on the drift line. The ones shown below were featured in Browns Put On a Shine in the Drift Line.


A Puzzler

How about this one? If you know what this one is, please let me know. Check out the bullae on the blades. The blades are so shiny they inspired Browns Put On a Shine in the Drift Line.

A mystery brown with shiny blistered blades


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 brown 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 browns.

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

The Seaweed Sorter app is fun and very useful!

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