By Sheldon Greaves, Ph.D.
All photos by the author.

This article was written in early January of 2007, but never published. This seemed a good time to dust it off and present it as an invitation to the delights of exploring tide pools.

Coming Home

After five years on the east coast, we moved back to California. The last few days have formed an extended reunion with old friends and favorite places. One of these is a state beach called Pescadero, located along Hwy 1 between Santa Cruz and Half Moon Bay. While returning from a visit with a family friend who lives in Santa Cruz, we stopped at Pescadero to re-aquaint ourselves with this gem. Coincidentally, when we arrived the tide was lower than it usually is, and so we scrambled out into the exposed intertidal zones to see what could be found.

The Intertidal Zones

Tide-pooling was one of my favorite activities when I was younger, and continued to be so well into early adulthood. I was raised in Salem, Oregon, only about fifty miles from some of the most incredible tide-pooling sites in the country where an offshore upwelling of cold waters bring vast quantities of nutrients to feed the base of the intricate food pyramid of seashore life. At the age of eleven or so I somehow was introduced to the classic Between Pacific Tides by “Doc” Ricketts, himself an amateur scientist and a close friend of John Steinbeck. Ricketts was the inspiration for the character “Doc” in his novels set on Cannery Row. Primed with Rickett’s book and a dose of Jacques Cousteau for good measure, I would pester my parents incessantly to have the next family outing in Lincoln City or Florence or Depoe Bay near my favorite haunts. When the weather was unsuited to exploring tide pools, I could visit the indoor tide pools maintained at the coastal oceanographic research museum run by Oregon State University.

Intertidal ecosystems are one of the more dramatic examples of what biologists call the “edge effect.” This describes what happens when two different kinds of ecosystems come into contact with each other, such as when a forest borders an open field. Along that margin, life forms are typically more diverse and more profligate. In the zone between the tides, where land and ocean meet, a healthy ecosystem can practically explode with different life forms native to that environment. Other creatures not usually associated with seashore environments, such as crows, foxes, and herons will come to feed on animals found there.

My favorite part of Pescadero is a section of tilted strata consisting of jointed sandstone. The layers are tipped to about 40° and run almost perpendicular to the shoreline, out into the ocean for nearly one hundred meters. The joints in the sandstone have been widened by wave action to create numerous pockets where tide pool critters thrive. And since this formation is still mostly solid and not a jumble of loose boulders and smaller stone, you don’t have to worry so much about a loose rock tripping you up. Believe me, taking a tumble while investigating tide pools can be painful.

Safety and Etiquette

While scrambling around on smooth rocks slick with seaweed, today’s tide pool enthusiast might borrow an idea from the skateboard fraternity and invest in a set of knee and elbow protectors. A pair of knee pads of the sort used by contractors who install flooring or must otherwise work on their knees is good to have and are available at most larger hardware and home improvement stores for around fifteen bucks. Footwear should be something you don’t mind getting wet and will allow a good purchase on wet, treacherous rocks. A pair of old tennis shoes is a good choice, but note that some rubber soles grip wet rocks better than others. Wading boots are also a good choice, although they create the temptation to wade through a tide pool, which can damage the pool’s environment. Still, I find that the soles of wading boots usually grip the rocks better.

In my younger days, tide-pooling was still one area of natural science where collecting was considered appropriate, but no more. This popular pastime has caused considerable damage to many tide pool areas where people have easy access. Most intertidal marine invertebrates are very fragile, and unless you really know what you’re doing, your specimens will disintegrate quickly leaving you with little to study. The one exception to the ban on collecting is the realm of the microscopic. Plankton studies are a rich field of scientific discovery waiting for ambitious amateurs to harvest. Most macroscopic denizens of the average tide pool begin life as microscopic larvae. Moreover plankton is literally the foundation of nearly all oceanic ecosystems, so understanding it is critical to assessing the health of the world’s oceans. That said, the amateur scientist may bring home a sample of plankton in a jar of seawater without harming the local environment.

Curating the Trip

For the larger plants and animals, today’s tide pooler can use the amateur scientist’s tool for all trades, the digital camera. The smaller, lighter models of today won’t encumber you while clambering from pool to pool. Make sure your camera has a macro feature because you will be making a lot of close-up shots. Since tide pool creatures often use crevices and overhangs for protection, you may need to get into some tight places or spend some time kneeling down on a rough surface to get just the right shot.

Our survey of the Pescadero tide pools yielded some of the usual suspects. Starting from the lower reaches that are usually covered by water, we found some such as ocre stars (Pisaster ocraceous), and scattered examples of green sea anenomes (Anthoplura xanthogrammica) and pink-tipped anemones (A. elegantissima). Moving further up the tidal zones were mats of mussels (Mytilus sp.) and goose barnacles. Continuing into the “splash zone” that is kept wet through spray and higher tides we spotted turban snails and several species of limpets. This trip we were pleased and surprised to find a purple sea urchin (Strongelocentrotus purpuratus) in one of the lower pools. These animals had become less common in the years prior to our departure from California. We also found formations of tube worms of a type I don’t remember seeing before and which do not appear in any of my other field notes.

Taking notes is mandatory for the serious field naturalist, and tide pooling is no exception. My notes were made after the fact once we were on surer footing. Use a cheap pocket notepad and a pen with waterproof ink (the Uni-ball vision roller ball pens are available everywhere and are both waterproof and fade proof). Specialty supply houses that cater to professional naturalists and forestry workers also sell note pads with special paper that you can write on even when it’s wet. Try to arrange your observations by tidal zone. Start as far out as you can go safely, since if it is low tide, this zone is usually underwater and not open for observation. Gradually work your way inland, but don’t rush it. Take your time and look carefully at the rocks and pools in front of you; intertidal organisms are adept at hiding themselves. Look carefully and have a good guide to seashore creatures waiting on higher ground. Trust me, negotiating a field of tide pools needs both hands and a field guide can be a frustrating nuisance at such times. Take a photo of unknown organisms with your digital camera and identify it later at your leisure. Some time spent in advance preparation with a field guide or a more comprehensive book like Between Pacific Tides for western shores will be time well spent preparing for field observations.

One final note: the ocean can be a treacherous and deadly menace. A rogue wave can sneak up on you when you are engrossed in your observations and spill you or even sweep you out to sea. Carry a first aid kit for the odd scrape from barnacles or bumps and bruises or mild sprains.

Finally, you’ll want to finish your tide pool adventures with a nice lunch or dinner. If you’re at Pescadero Beach, drop by Duarte’s in the town of Pescadero about a mile inland for their outstanding cream of artichoke or cream of green chili pepper soup. And if you happen to be tide pooling in the vicinity of Taft, Oregon just south of Lincoln City, your day is not complete without lunch or dinner at Moe’s ”best clam chowder on the west coast.”

Note: all photos for this article were taken with an Olympus SP-350 digital camera.