Ventura County in Early June – The Tidepooler

Tide Pooling Log: Ventura County in Early June

June 17, 2024

Summer in California brings extremely low tides, but only in the very early hours of the morning. While not great for sleep schedules, these tides offer a great opportunity to see nocturnal animals you won’t see during the day and a chance to visit the intertidal without the crowds that daytime low tides bring. 

I was privileged to tide pool during multiple of these low tides early this month in several locations. The first location was in Ventura County, farther north from where I usually visit. We were beach camping on a break wall that stretched out onto a sandy beach. I knew from previous trips that there were cobbles and small boulders submerged just beyond our campsite that were only exposed at the lowest of tides. So I woke up within the 4 o’clock hour and went out to see what I could find. 

Unlike many of the beaches in Orange County where the tide pools are formed over bedrock, this beach was sandy with stones too large to be moved by the surf sunken into the sand. The rocks are exposed to a fair amount of wave shock as the coast isn’t protected here, but they are well beneath the water during a moderately low tide of around 1.5 ft. They were just barely above the surface at mean low water (0.0ft) and entirely exposed at -1.4 ft when I began exploring.

Despite being June, it was cold this early; the sun wouldn’t rise for almost another hour and it was misting so much that it was practically drizzling. I wore my boots to keep my feet warm and hoped a wave wouldn’t come and flood them. 

Algae Zones

The tide this morning was -1.4ft but was already coming back in by the time I began. Even though these rocks were far below the typical low tide, there were still specific zones I noticed in algae growth, probably resulting from how deep underwater the rocks usually are. Algae is not my forte and I don’t usually talk about it here, but I’ve come to appreciate how much algal growth in the intertidal can tell you about the location. And, of course, I can appreciate that it forms the basis of the food chain for intertidal invertebrates, in addition to planktonic food. Noticing the algae where I might have been tempted to ignore it prompted me to ask further questions and gain more understanding about this coastline than I would have otherwise.  

Where the boulders began in the sand, sea lettuces (Order Ulvales) were the primary algae. Extremely slippery, this algae grows on rocks in shallow water that receives lots of light. It can withstand a wide variety of temperatures and thus grows high in the intertidal, often seen somewhat dried up and out of the water at low tide. High intertidal sessile and slow-moving animals like mussels, barnacles, chitons, anemones and limpets made their homes among the sea lettuce.

Moving toward the waves, surfgrasses took over. Belonging to the Genus Phyllospadix, these flowering plants aren’t algae but vascular (like land plants). They are found on many rock shores, but lower in the intertidal, providing a unique habitat for many species. This was the most prominent plant seen on the rocks that would be exposed from about -0.5ft to -1.5ft. 

Finally, where I could barely walk without flooding my boots, kelps (Order Laminariales) became the prominent algae on the lowest rocks. These green algae create large forests offshore and can live in deep water, growing tall toward the surface to reach the light.  

The breaks between these zones were stark and evenly spaced along the rocks. While many prefer to zone the intertidal based on invertebrate life, algae is another reliable way to parse out sections. Even if it isn’t your favorite, don’t ignore the algae on the coast; it can tell you a lot about how often the area is exposed to air and what kind of wave shock it experiences. 

Animal Life

High on the break wall boulders, as well as on the exposed rocks, were all the typical — yet fascinating — rocky intertidal creatures. Limpets of all kinds, acorn and gooseneck barnacles, mussels, aggregating anemones, and many other species. The tides during the day that dropped only to about 1.5ft exposed these rocks, so I headed out toward the lower intertidal. But these animals remained on most of the cobbles and boulders as I moved toward the waves.

The first animals I noticed were the anemones. While we usually think of anemones as rocky shore animals, they are also very prominent on sandy shores, burrowing their columns deep into the sand. Aggregating anemones (Anthopleura elegantissima) smothered the rocks while larger sunburst anemones (Anthopleura sola) were “planted” in the sand. It was a treat to find a moonglow anemone (Anthopleura artemisia). This species almost exclusively burrows and has exquisite stripes and colors along its tentacles.

Red-banded transparent shrimp (Heptacarpus sitchensis) were also out and about before the sun started to rise from behind the hills. These nocturnal animals are speedy when they decide to be, but some individuals let me get quite close with my camera. 

After searching around the base of several larger rocks, I spied this eelgrass isopod (Pentidotea resecata). He was easy to see with his bright green coloration which usually helps them blend while living on eelgrass or surfgrass. But this one seemed to prefer the kelp. Although best camouflaged on eelgrass, these isopods live on a variety of other green and brown algae as well. The silt in the water, the low light, and his position far under a small boulder made him difficult to photograph.

Among the rocks and surf grass, I also saw multiple sea spiders. These uncommon creatures look like crustaceans but actually belong to Order Pantopoda. They are notoriously difficult to find and photograph, so I don’t have a definite ID on these animals, despite having taken better than when I had seen them previously.

I didn’t expect to see any nudibranchs this morning, but I was surprised when I found this tiny slug in the genus Eubranchus floating using surface tension. I offered my finger for it to latch onto before placing it on some algae so it wouldn’t get tossed around when the tide returned. Sometimes nudibranchs float on purpose as a form of locomotion. I was very surprised to see such a small slug in this rough area; you can see how small it is compared to the lines of my fingerprint. A fellow naturalist identified this slug as a homely aeolid (Eubranchus rustyus). I disagree with the common name. Although tiny, this animal is quite beautiful if you have the time and equipment to look closely. And yes, both the photos above are of the same animal; lighting and background can greatly affect what details you can see in your photo.

As the tide began to return, I moved further up in the intertidal and saw many chitons. These mollusks aren’t nearly as well-known or studied as snails or slugs, perhaps because they lack some of the more complex life functions of other groups. They are often quite beautiful when seen up close, but are unfortunately very difficult to identify. I saw several California spiny (Nuttallina californica) and mossy chitons (Mopalia muscosa). Along with a couple of individuals that I haven’t been able to identify either on iNaturalist or with my field guide. The one in the center is most likely a Keep’s chiton (Cyanoplax keepiana). The two in the photo on the right seemed to be crawling over each other!

One of my favorite finds of the day, however, was one of my last: this Kellet’s whelk. Usually a subtidal species, I didn’t even know what this snail was before finding this giant. These snails are primarily scavengers and known for their yellow and black mantles. I was super excited to find a live one that was so large, around the max known size for this species at 7 to 7.5 inches. As a slow-growing snail, this indicates it was probably over ten or 15 years old. The lack of beach combing traffic on this relatively unknown beach coupled with its low intertidal home might have contributed to its long life. This animal is commercially harvested and a shell this large would be prized by shellers, but it was covered by the tide soon after I left it. 

The tide had come in and covered most of the low intertidal boulders. While ambling back to our campsite, I saw the tracks of a raccoon scavenging among mussels in the high intertidal and the trail of mussel shells it left behind. Even coasts that aren’t “known for tide pooling” can harbor much intertidal life if you know what to look for.