I Went to the Intertidal During a “High” Low Tide; Here’s What I Found – The Tidepooler

I Went to the Intertidal During a “High” Low Tide; Here’s What I Found

July 1, 2024

During the lowest of low daytime tides, you’ll find hordes of people at popular tide-pooling locations. Everyone knows that you have to visit during the lowest tides to see the best stuff, right?

Well, kinda. For the intertidal enthusiast, visiting during the lowest tides is the only way you might see the rare low intertidal species you are after. But these animals are usually small, cryptic, and not particularly exciting without context about them. For the casual tidepooler or beachgoer, these lowest tides probably won’t provide any more of the large and interesting animals than a moderately low tide. Plus, you can avoid the big crowds. Depending on what you’re looking for, a 1.0ft tide is just as good as a -1.0ft tide. 

To show you what I mean, this article will catalog what we saw on a small rocky outcropping and the surrounding sand during an afternoon low tide of 1.7ft. Ordinarily, I wouldn’t have visited the tide pools at such a “high” low tide, but we were visiting in Ventura County and I wanted to see what we could find. 

On the Outcropping

I knew that most of the low intertidal rocks at this location wouldn’t be accessible. Only a few of them jutted out of the water past the waves, where several Pacific harbor seals (Phoca vitulina ssp. richardii) were basking. We watched them tussle for space and lift their tails and heads when the wave came, making their bodies the shape of a smile. Further south, we predominantly see California sea lions (Zalophus californianus), so we enjoyed getting a better look at these seals. 

As we walked south along the beach, we came upon a large outcropping of rocks that was higher in the intertidal and exposed for exploring. Right off the bat, we saw many of the sessile and semi-sessile animals of rocky shores. California mussels (Mytilus californianus) reigned on the high parts of the rocks while aggregating anemones (Anthopleura elegantissima) took over toward the bottom of the boulders, spending more time submerged. Gooseneck barnacles (Pollicipes polymerus) also made an appearance on the seaward-facing sections of the rocks.

The larger sunburst anemones (Anthopleura sola) were also prevalent here on the sides of the outcropping where they would receive less sun. They dropped down toward the ground while out of the water, giving us a chance to see their long columns armored with shells and pebbles that are usually hidden or remain unnoticed. 

There were a few chitons about too. Many California spiny chitons (Nuttallina californica) and even a mossy chiton (Mopalia muscosa) here and there. And I also loved seeing the variety of limpets here. There were several large owl limpets (Lottia gigantea) and many congregations of finger limpets (Complex Lottia digitalis) huddled together in nooks and crevices to escape the sun. 

In the Pools

Most of these animals were attached to the larger outcropping and entirely exposed to the air. But higher in the intertidal were several shallow pools created by small boulders. Despite being more frequently exposed by the tide, the pool microhabitat ^(https://www.blogquicker.com/goto/https://thetidepooler.com/2024/01/16/microhabitats-inconsistencies-in-the-intertidal/) made them hospitable to several animals not ordinarily seen at the 2.5ft mark. Unlike many of the rocky areas I usually visit, these pools were created by small rocks surrounded by sand and largely had sandy bottoms instead of rocky substrate.  A few large wavy turbans (Megastraea undosa) were crawling about in these sandy pools, which was surprising to me as they are typically a low intertidal, rocky shore animal. 

I was also excited to see three green bubble snails (Haminoea virescens). I had only ever seen one of these before, but two of them were hanging out together. These are headshield slugs, possessing a small, delicate shell that can’t even fit their entire body! Feeding primarily on algae, they blend in very well, especially when sand sticks to their mucus coating, further obscuring them. 

Finally, perhaps the best find of the day was in a small, sandy pool beneath a tiny pebble, no more than an inch or two across. Peering out from beneath, one of either side, were Cabrillo porcelain crabs (Petrolisthes cabrilloi), a new species for me. These crabs are anomurans, in the hermit crab family, and aren’t very common on California’s coast. While there are several species, their preference for under-rock habitat means they aren’t often noticed. Why these were hiding on this pebble, I’m not sure, especially since such a small rock couldn’t have afforded much shelter once the waves returned and tossed it around. I was even more surprised when I picked up the pebble and several more porcelain carbs, most smaller than the first two I saw, scurried out. After getting a few shots, I returned the pebble and let the crabs crawl back underneath their home. 

It was remarkable that these crabs were hiding in such a small pool, under such a small pebble, this high in the intertidal.

On the Sand

We also had several finds away from the rocks on the sand. There were hundreds, if not thousands, of Pacific sand crabs (Emerita analoga), the tiny sand-dwelling animals that children dig up with plastic shovels. These animals often move up and down the beach with the tide, so you can find them where the waves backwash no matter the tide. They are lightning-quick at burrowing and thus very difficult to photograph while on the sand. 

There was also a mass stranding of salps, colonial tunicates that live in the water column. They look like gel blobs and are often mistaken for sea jellies. The ones we saw didn’t have very defined shapes, so it was difficult to tell the species, as they may have just been pieces broken off a whole animal. 

A dead rock crab, possibly a yellow rock crab, was washed up on the beach along with a California spiny lobster (Panulirus interruptus). I couldn’t tell if the lobster tail was from a dead animal or only a molt of an animal growing larger. 

Finally, one of the most fun finds of the day was this swell shark egg, which appeared to be successfully hatched. Sometimes called mermaids’ pursues, these shark eggs are attached to kelp or the substrate until the hatchling breaks free. I hope this small swell shark is still swimming happily, growing into an important member of the ecosystem.

Turns out, you can still see amazing intertidal life, even when the tide isn’t very low. Don’t let your expectations stop you from enjoying and exploring this remarkable habitat.