Revisiting the Great Tidepool

Sunday, August 13, 2023. It was a decent low tide, less than a foot below the MLLW (mean of lower low water), the “0” of tide tables, but still low enough to easily get into the mid-intertidal zone. And at a decent hour too, a little after 0-dark-thirty. It was already starting to get light when I parked at the empty north Cape Arago parking area1. I could hear the sea lions barking from Shell Island, in North Cove. But I went south, down a steep informal trail that snakes down to Middle Cove. 

Middle Cove, Cape Arago, looking north, August 2023

Sometimes when it’s wet this trail is very slippery; today it was dry and easy. I crossed the field of boulders that form a sort of tombolo to a higher rock in the cove, aiming for my old PhD research tidepool. When I was doing that research, for several summers in the late 1970s, I made this trek so many times I could have done it in my sleep. Some of the rocks along the route are dark grey sandstone, but weathered by the surf to reveal a trove of white shells embedded in them. Crossing here gives a sense of time travel; of crossing an ancient intertidal that was once here, then full of clams and snails, then buried and fossilized, and now resurrected again to the light and wonder as we navigate across it.

Intertidal boulder with fossil shells, Middle Cove, August 2023

I last visited this place in 2017, and wrote about it in a blog called “The Great Tidepool.” There I told the story of how somehow my history and karma had led me here to the Oregon coast, the first time more than 50 years ago, and how my “Great Tidepool” reflected the influence of Edward F. Ricketts, a polymath marine biologist2 of a complicated era just before I was born. Ricketts, who lived and worked in Pacific Grove, on Monterey Bay in California, had his own “Great Tidepool,” used as a metaphor for the human condition and political situation of the time in John Steinbeck’s novel about Ricketts, Cannery Row3

Doc was collecting marine animals in the Great Tide Pool on the tip of the Peninsula. It is a fabulous place: when the tide is in, a wave-churned basin, creamy with foam, whipped by the combers that roll in from the whistling buoy on the reef. But when the tide goes out the little water world becomes quiet and lovely. The sea is very clear and the bottom becomes fantastic with hurrying, fighting, feeding, breeding animals.

In my 2017 blog essay, I wrote: 

What was I looking for in my Great Tidepool? Looking back now, I think I was searching for the same thing Ed Ricketts was searching for. I wanted a conversation with another world. I wanted to ask a non-human species some questions that related to my own life, and to what was going on in the wider world around me. I wanted to look from the tidepool to the stars and then back to the tidepool of human society again. Is behavior adaptive? Does it matter, what we choose? Is my species likely to survive?


When I finally got to the pool that I’d spent so much time in during my graduate school days, and which I’d visited again only six years ago, I was struck by the changes. It was déjà new—not déjà vu! What I remembered was a large swath of algae climbing the sloping rock face above the pool surface for more than two meters at low tide, more than my height, and the algae clearly zoned into bands by their colors. Now there was only a scraggly band of brown algae rising a meter or so above the pool surface, and none of the yellow-green rockweed (Fucus sp.) that I remembered in the upper zone. The brown algae in the lower zone were sparse, like an overgrazed pasture might look.  

My PhD-research tidepool, looking south, August 2023

I really wasn’t expecting to see such a change. Somehow my image of my Great Tidepool was of immortal stability—OK, a dynamic ecological balance perhaps—but relatively stable nonetheless. And that’s how it seemed on my last visit half a dozen years ago, very similar to when I was doing my research there in the 1970s. But a curious naturalist’s first task is to look and see, and I was seeing an obvious change. Second inclination is to wonder “Whoa! What’s going on here?” I immediately started looking closer to try to figure out what was different. 

The first thing I noticed was that the rock slope above the pool, and the tidepool too, were jammed with more small black turban snails (Tegula funebralis) than I ever remember seeing. These little guys were my research critters, my friends, and I got to know them even as individuals during several years of intimate study.4  Now, they were everywhere, at densities much higher than I’d seen in the 1970s, or in 2017, and smaller, on average. 

Rock wall above tidepool with black turban snails August 2023
Closeup, black turban snails: more hungry mouths than food, August 2023

The second difference that struck me was that I saw no sea stars (sometimes called starfish). None, zip, zero. Pisaster ochraceous, the ochre sea star, is the top predator in these intertidal latitudes, a keystone species that articulates the ecology of the place. Robert Paine, an ecologist from the University of Washington, coined the term “keystone species” based on his research on this species at Mukkaw Bay, Washington. Mukkaw Bay was another of my PhD research sites, chosen mainly because of Paine’s work there. This sea star is a major predator of black turban snails, and my research showed that the snails react behaviorally to its presence, and that it affects their habitat choice within the intertidal zone. Black turban snail populations (like those of the California mussel) are probably held in check by ochre sea star predation. 

Ochre sea star, Middle Cove, Cape Arago, in August 2017

A hypothesis began to form immediately. In my 2020 book about the Cascade Head Biosphere Reserve5 on the Oregon coast not too far north of here, I’d written about “sea star wasting syndrome,” abbreviated “SSWS,” a still-mysterious disease—or some more complicated constellation of factors—that, beginning suddenly in about 2013, caused populations of the keystone ochre sea star, and many other sea star species, to crash. When a keystone species crashes and almost disappears, ecological theory predicts that big ecological changes, called “trophic cascades,” may appear. 

When I finally looked at a photo of my Great Tidepool from my last visit in 2017—by luck almost a perfect match to my recent photo (above) in viewpoint—my memory of a big ecological change was confirmed. The 2017 photo showed that the entire upper band of rockweed (Fucus sp.), yellow-green in color, is missing now, in 2023, apparently gobbled up by a hungry herd of black turban snails!

Nearly the same view of my research tidepool taken in August 2017

When their sea star predator’s population crashed because of SSWS, black turban snail populations must have baby-boomed in response, and they are now eating up a lot of the algae that used to cover the slope above my Great Tidepool. That’s the explanation, I think, for what I was seeing this time (in 2023) in Middle Cove. 

Could there be some analogy here to the population explosion of my own dear species? The human population has been exploding exponentially now for centuries (even millennia, if you look as far back as the invention of agriculture maybe 10,000 years ago), and our one single species is now gobbling up the ecosystems of Earth, leaving them sparse and overgrazed like the algae above my Great Tidepool. 


And that brings me back around to what I now consider, in retrospect, the philosophical underpinnings of my PhD research. As I wrote in the earlier blog, I was not just interested in where black turban snails chose to crawl in relation to the surface of a tidepool at Middle Cove, Cape Arago, Oregon. What I really wanted to know was what that might have to tell us humans about how our behavior might be adaptive… or, as I suspected and feared, even then, maladaptive. The same deeper question, I think, that Ed Ricketts and John Steinbeck had about the meaning and importance of understanding tidepool life in the midst and aftermath of WW II.

My PhD research concluded that animal behavior can evolve in adaptive ways. But the undercurrent in my mind, even then, was: What about human behavior? Is our behavior adaptive? When, and why? We are a hyper-cultural species, and when culture is influencing behavior so strongly, could we get ourselves into a trap in which our behavior is not ecologically adaptive anymore, but actually threatening to our survival?


I went back to Middle Cove a decade after my PhD research to initiate another study of habitat-choice behavior in an intertidal gastropod, a distant cousin of the black turban snail, this time a limpet, Lottia digitalis, the ribbed limpet (its usual common name). Limpets are basically snails whose shells are shaped like a dunce cap or a cone, without a spiral. As abundant as black turban snails, this species is everywhere in the mid-intertidal at Middle Cove. Then, in the late 1980s, I brought my young family with me as field assistants. My daughter, age five, helped with the fieldwork, finding and counting limpets; my son, age one, splashed in tidepools in diapers, enchanted by hermit crabs, sculpins, and all the other critters scurrying in the Great Tidepool. That research was published in 1989 as: “Habitat-Choice Polymorphism Associated with Cryptic Shell-Color Polymorphism in the Limpet Lottia digitalis.” 

The gist of that study was that some ribbed limpets have evolved white shells with black markings that make them camouflaged when they rest on goose barnacles, and others have brown shells that match the rocks nearby. Black oystercatchers are their main predator; those birds hunt visually, creating a selective force that favors habitat choice by the limpets. Even John James Audubon’s old painting of the black oystercatcher pictured them hunting limpets!

Goose barnacle cluster with white-and-black camouflaged ribbed limpet (almost center of photo), August 2023
File:427 I. White-legged Oyster-catcher - 2. Slender-billed Oyster-catcher.jpg
The Black Oystercatcher, Haematopus bachmani, by John James Audubon, Plate 427, Birds of America

If a white-and-black limpet fails to crawl back to its barnacle-colony home after a nighttime of grazing out on the surrounding rocks, it’s much more likely to get eaten than than a brown limpet. My study showed that the limpets chose to rest on the substrates where they were camouflaged, brown shells on brown rocks, white-and-black shells on goose barnacles. In limpets, behavior was apparently ecologically adaptive, as in black turban snails. I was still trying to be an academic ecologist—publish or perish—but, again in retrospect, I was really still asking the same question about my own species. Is our behavior ecologically adaptive?

On this visit in 2023, I looked for my old research sites for that limpet study, but was not able to find the island-like clusters of goose barnacles on relatively barren rocks that I remembered. My hypothesis regarding that change is that the mussel and goose barnacle landscape on these intertidal rocks may be a shifting mosaic, and since the amount of mussel-bed cover on the rocks is controlled by sea star predation, the sea star wasting syndrome outbreak in 2013 may have remapped this intertidal zone since my research so many decades ago. My impression is that there is now less bare rock, more mussels, and fewer islands of goose barnacles than when I was doing the limpet research in the late 1980s, when ochre sea stars were still the ascendant keystone species controlling the mid-intertidal community.

Ecological relationships are dynamic, but also resilient. I looked at many goose barnacle colonies, and all hosted the camouflaged white-shelled variant of Lottia digitalis I’d studied. I took a photo of one circular colony, because I had initially spotted three camouflaged limpets on it. When I looked closely at my photo later, I found ten. 

Goose barnacle colony with ten camouflaged limpets, August 2023


Shifting back to philosophical ecology again, as I did with black turban snails, is there any analogy between the obviously ecologically adaptive behavior ribbed limpets exhibit and that of my own beloved species? Yes… but I’m afraid that while ribbed limpets obviously do what is ecologically right, my species seems often, now, to be doing the opposite.

Oh well… so what is a curious naturalist, as I described myself earlier, to conclude? 

A pessimistic conclusion would be that if we keep at our maladaptive behavior, we won’t survive. We’ll get eaten by the hungry predators of evolution—they are surely waiting out there for a bad adaptive move, like a white limpet that settles on a brown rock. An optimistic vision would be that evolution will shape our cultural behavior in adaptive ways. We’ll crawl onto our little patches of white barnacles, not get too big for our britches, and learn to live sustainably in our little part of the biospheric intertidal zone, sharing the rest of it, the much bigger part, with our other relatives in the biotic community. 

Looking south from Middle Cove, August 2023


Back home, I pulled a couple of volumes off my library shelves, thinking of the phrase “the outer shores.” I’ve been an acolyte of Edward Ricketts since high school because of my encounter with his book Between Pacific Tides (described in my 2017 essay). And so, at about the same time as I was finishing my PhD research in the late 1970s, I bought a copy of The Outer Shores, edited by marine biologist Joel Hedgpeth,6 which brought together a collection of Ricketts’s most philosophical and personal writing. That writing captured “Doc’s” wide-ranging, holistic worldview, and that’s what led me to call him a “polymath marine biologist” in my previous blog. He had a Humboldtian inclination to connect his science with everything else in the universe. The titles of the three philosophical essays collected by Hedgpeth point at this eclecticism: “Essay on Non-teleological Thinking,” “The Philosophy of ‘Breaking Through’,” and “A Spiritual Morphology of Poetry.” 

Ricketts’s ideas were shaped by his friendship and conversations with John Steinbeck and Joseph Campbell. From those names alone you get a sense of Ed’s span of intellectual interests, from mythology to literature and social justice. It’s all happening in the Great Tidepool, “fantastic with hurrying, fighting, feeding, and breeding.” (Although someone once claimed it’s all happening at the zoo!) Looking into, or maybe out of, that Great Tidepool, Ed Ricketts saw a vision of “breaking through.” Of somehow escaping the karma of the human social and political morass of his time. That phrase, “breaking through,” came from a poem by his (and Steinbeck’s), neighbor and friend, the great and now almost forgotten Californian poet Robinson Jeffers. In his poem “Roan Stallion,”7 Jeffers wrote:

Humanity is the mould to break away from, the crust to break 
through, the coal to break into fire, 
The atom to be split. …

Jeffers’s poem was published in 1925. Hitler was rising to power in Germany in the hot ashes of the “the war to end all wars,” World War I. Any astute politician and intellectual could see what was coming. The 1920s were a disillusioned time—not so different from now, a hundred years later, I think, sadly. 

When Ricketts was writing his philosophical essays, he and Steinbeck and their Carmel neighbor Robinson Jeffers were living through what had emerged in the hell of geopolitics of the era: World War II. Looking back, I think only a revisionist historian or philosopher could criticize them for their view that “humanity”—the human species, and all our hurrying and fighting—was totally messed up, and maybe not worth it in the cosmic big-picture. 

I wrote about my debt to Jeffers, as an ecophilosophical ancestor who has shaped my worldview, in a 2014 blog Not Man Apart: Genealogy of an Ecological Worldview. In that story I didn’t mention that Jeffers, who was featured on the cover of Time magazine in April, 1932, was later criticized and even ostracized because he wasn’t a rah-rah supporter of US involvement in WW II. Along with Steinbeck and Ricketts, he was sick of the human stupidity and disfunction of the time. 

I don’t think Jeffers was necessarily opposed to taking a moral position against an evil actor like Hitler, but just sick and tired of the same old human stupidity. What a dumb species! This wasn’t misanthropism—“human hating”—it was more like realism. Jeffers’s philosophical view was labelled “inhumanism.” But again, that didn’t mean hating humans, just hating the destructive, self-absorbed, self-aggrandizing penchant of our species, our human supremacism (to use a modern term that wasn’t in his lexicon). My sympathies are with him.
Robinson Jeffers on the cover of Time, April 4, 1932

Ricketts could see what I had to get a PhD-full of data to demonstrate: that in the Great Tidepool of Life on Earth, the hurrying-fighting-feeding-breeding behavior of every other species made ecological and evolutionary sense. It was adaptive and sustainable. In humans? Well, often not! 

Hence, the conclusion, both scientific and poetic, that “breaking away” from the stupidity of our own species was where our ecological and evolutionary, and also our philosophical and spiritual, future as the human species had to go. 

Guardian of the Great Tidepool (probably a lesser yellowlegs, Tringa flavipes), August 2023

And has to go, still now. Unfortunately, still now. Wading in the tidepools of Middle Cove again, I was wading into those same, rich and roiled waters. Species may shift, climates may change, sea levels may rise, but the real questions, quandaries, and answers don’t. 


For related stories see:

Notes and sources:

  1. Cape Arago State Park, near Coos Bay, Oregon
  2. Edward F. Ricketts and Jack Calvin. Between Pacific Tides. Fifth Edition (Stanford, CA: Stanford University Press, 1985).
  3. John Steinbeck. Cannery Row (New York: Viking Press, 1945).
  4. Habitat Choice in the Intertidal Snail Tegula funebralis. B.A. Byers and J.B. Mitton. Marine Biology 65: 149-154 (1981); Enzyme Polymorphism Associated with Habitat Choice in the Intertidal Snail Tegula funebralis. Bruce A. Byers. Behavior Genetics 13: 65-75 (1983)
  5. The Outer Shores. From the Papers of Edward F. Ricketts. Introduced and edited by Joel W. Hedgpeth. (Eureka, CA: Mad River Press, 1978).
  6. Bruce A. Byers, The View from Cascade Head: Lessons for the Biosphere from the Oregon Coast. (Corvallis, OR: Oregon State University Press, 2020).
  7. Roan Stallion
  8. Tringa flavipes, Lesser Yellowlegs

About Bruce Byers

Bruce Byers Bruce Byers is an ecologist, writer, and international ecological consultant. His creative nonfiction writing tells stories of science and conservation from around the world. As an independent consultant, he assists government agencies, NGOs, and the private sector in the United States and worldwide with strategies for conserving biodiversity and improving the human-nature relationship.


  1. Charon Geigle
    September 28, 2023 6:40 pm

    I continue to enjoy reading as well as pondering on your essays. Thank you, Bruce.

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