Tide Pooling Log: Orange County Eelgrass beds Before Dawn
Most of my tide pooling as a kid was on rocky shores where it’s easy to spot animals and there is an abundance of life. But recently, I’ve been educating myself about sandy and muddy shores and finally got a chance to visit a sandy beach with sevearl eelgrass beds during an excellent low tide this summer. With a small group of other tidepoolers, we planned to meet around 5 am on a small public beach in an Orange County harbor. I had spent many days at this beach as a kid but had never gone with the purpose of tide pooling. It is entirely protected from surf and I knew had both sand flats and eelgrass beds.
I had an idea of what kinds of animals to look for on this beach but was not prepared for the sheer abundance and diversity of life. While arguably not as picturesque as rocky shores with its fishing pier and sea wall, this little beach had a ton to offer us.
It was still midnight-dark when we got to the little beach. I carefully made my down the steep stairs to the sand, walked beneath the fishing pier, and found a couple of my friends near an eelgrass bed with their headlamps and flashlights. This area is often exposed but usually inaccessible because it is headed by a private beach. But at low tide, you can walk around the docks and wade in the water below the beach. It was near -1.7 low tide this morning, so we easily accessed the area.
Right away, I started looking for my target species: the Taylor’s seahare (Phyllaplysia taylori). Extremely cryptic and seldom seen, this seahare perfectly matches the background of its eelgrass home, which it seldom, if ever, leaves. They are known for being exceedingly difficult to find due to their small size and excellent camouflage. One of our group said that she and a friend had searched for 6 hours only to find a single adult. But I was determined to find one if they were here at all.
I immediately started seeing their eggs, laid in gelatinous clumps on the eelgrass. A good sign, but not always an indication that adults are present. These animals also like to hide at the base of the eelgrass where the blades meet, making them even more difficult to spot. But it wasn’t five minutes before I called out, “Hey guys, I got a Taylor’s!”
They didn’t believe me at first, but soon came and saw for themselves. Perfectly aligned with the blade of the eelgrass, even growing to its exact width, was an inch-long Taylor’s seahare, stunningly green and delicately striped. Once I took a few photos, I let one of the other tidepoolers have a chance to get some shots. I was ecstatic; it was gonna be a good day.
While they were looking at the first slug, I knelt down again to search and found another one. And another. And another! There were so many grazing on the eelgrass we eventually stopped counting, but between all of us, I think we saw upwards of 25 that morning. These animals are fascinating, beautiful, and perform vital cleaning services to the eelgrass that in turn absorbs toxins, prevents erosion, and serves as a nursery for commercially important fish and invertebrates. Check out this article ^(https://www.blogquicker.com/goto/https://thetidepooler.com/2024/06/24/californias-forgotten-seahare-the-taylors-seahare/) to learn more about the Taylor’s seahare.
After crouching down to take lots of photos, the small waves started lapping at my legs and pants. I eventually just knelt on my knees instead. I didn’t even notice the cold water; I was so excited to about the invertebrates.
While the Taylor’s were expertly camouflaged on the eelgrass, another sandy beach slug was out and about in big, obvious groups. The cloudy bubble snail (Bulla gouldiana) is a large headshield slug, about four inches long as an adult. They were mating and lying eggs this morning in what looked like giant masses of yellow string. With the shallow water, eelgrass, and egg masses it was difficult to get an unobstructed view of the slugs! The shells on these slugs are so thin they are nearly transparent and aren’t used for protection. Most of the bubble snail species I had seen has been an inch long at the most, so it was a treat for me to see these larger animals.
By now the sun was above the horizon somewhere behind the thick mist and low-hanging clouds, turning the sky a pale gray. But we kept our headlamps on to better see what was under the water. Moving away from the eelgrass, we began searching the seawalls and rocks along the edges of the beach. One of our group found a white smooth-horned dorid (Conualevia alba), a rather uncommon species that most of us had never seen before. Most likely a summer visitor to our waters, this species is rarely seen north of the Southern California Bight and is found throughout the Gulf of California. This individual was only about a centimeter in length.
There were also several larger Monterey dorids (Doris montereyensis) on the sea walls and pier piles. The one on the left was exposed to the air at this low of a tide.
Even with the abundance of life under the water, the dry sand itself offered us some finds as well. Sand stars of the Genus Astropecten were abundant on this beach. Usually remaining buried in the sand, they crawl up to the surface when exposed to the tide and then walk along the dry sand toward the water. By doing this, they leave star-shaped indentations in the sand, perfect footprints of where they were buried. A kind man going for an early morning paddle was moving some of them to the water. He didn’t need to though, since these stars do well exposed and live in the intertidal purposely.
In California, two species in this genus occur, the California sand star (A. verrilli) and the spiny sandy star (A. armatus). They two are virtually identical to the naked eye, making a species-specific ID nearly impossible in the field.
There were also several crab species about in addition to the shore crabs scuttling around the walls and pier piles. Several species of rock crabs were on the sand or in the eelgrass. One Pacific rock crab (Romaleon antennarium) that I surprised on the sand hurried into an empty clam shell and buried himself into it, quickly vanishing from view. I also spied a Xantus swimming crab (Achelous xantusii) with bright purple claws and carapace. He was less skittish and opened wide his claws in a threatening display. I backed off, both because I didn’t want to cause him undue stress and also because I wanted to get this picture before he retreated.
Our group was lucky to see two warty sea cucumbers (Apostichopus parvimensis) that indeed looked like lumpy, red vegetables about the size of a large zucchini. They were also both well below the lowest tide line, but we were little deeper than our knees when taking a closer look. I had never seen this species on exposed rocky coasts, although its usual preference for sandy or muddy substrate might explain this. The ICUN lists this species as vulnerable, so it was good to see two individuals here.
Perhaps the most surprising (to me) find of the day were three sea pens, clustered together in the sand. Yep, that’s right; sea pens in the intertidal. These cnidarians are related to anemones and coral. They are typically subtidal, but one of our group had seen them here before and was able to find them again. The tide was so low that they were sticking out of the water like bare little tree trunks with no branches. We came back to the stop when the tide had risen some and saw their feathery appendages waving as if in the wind. These small individuals, only about three inches tall, were probably slender sea pens (Stylatula elongata), but I haven’t been able to get a definite ID.
We found a few more nudibranchs as the tide was coming back in, including a San Diego dorid (Diaulula sandiegensis) with much darker coloration than the individuals we see on rocky shores. This one was dark tan while the usual suspects are cream, sometimes almost white. The difference probably comes from diet. Many nudibranchs are semi-transparent and/or have digestive systems that extend out throughout the body, making the diet of a slug change its color. This is especially useful for animals that live on their food source since they camouflage themselves by eating. This little dorid blended in perfectly with the sand.
The group also spotted several sorcerer’s dorids (Polycera atra) throughout the morning, mostly on the seagrass or near pier piles.
Much more common but no less pretty were a couple of purple olive snails (Callianax biplicata) I observed, making slow progress burrowing into the sand. These animals usually travel just below the sand’s surface and can be found by looking for tiny, moving bumps. Their shells range from deep purple to light periwinkle. When the snail is moving, its mantle extends up from the front of its shell and resembles a snowplow, pushing through the sediment, with a tiny “snorkel” sensory organ held aloft at the top. These snails live an average of about 10 years but can reach as old as 15 years.
Undoubtedly to the dismay of the nudibranchs, we also spotted a California Aglaja (Navanax inermis). More often referred to by its genus name, the navanax is a predatory headshield slug that would have gobbled up any of the other nudibranchs we had seen this morning. They are quite adaptable and can be found in both sandy and rocky habitats. This one was making its merry way across the sand, seemingly undisturbed by our presence. We also saw several bunches of navanax eggs attached to the pier.
Speaking of eggs, throughout the morning we had seen moon snail eggs casings, often called sea collars for their unique shape. Adults essentially mix the eggs with sand and form a structured circular mass. One of the tidepoolers who had explored the opposite side of the beach first said they had seen a couple of adult moon snails. These sand dwellers also like to travel just below the sand’s surface but are much bigger than the little purple olives. When we found them, both were semi-above the sand and were about five inches long. Probably Lewis’s moon snails (Neverita lewisii) by their size, you can thank these voracious predators for any seashell you have found with a perfect necklace hole in it. Ever wondered how that got there? Moon snails bore holes in the shells of clams and other mollusks with their strong radulas and suck out the soft body. Ergo, necklace seashells. I was so surprised and excited to see these animals as I hadn’t seen many observations of adults in this location.
We were up to our knees in water at the edge of an eelgrass bed when it came gliding over the seagrass with slow, lazy beats of its fins. A Haller’s round ray (Urobatis halleri). Also known as the little sting ray, this ray has a small body and a big barb full of toxin. As a shallow-water species, it stings hundreds of beachgoers a year, and although the sting isn’t fatal, it is rather painful. But this one had no interest in us and merely passed by a time or two while we stood still in an effort not to scare it. Almost without fail, they sting when they are stepped on in self-defense. I often encounter this species while kayaking, had never seen one this close that didn’t immediately dart away. Such a beautiful creature.
The sand seemed to hold a myriad of treasures, with more appearing the closer you looked. A tiny horseshoe worm, Phoronopsis californica, with no common name was a sessile inhabitant of the sand. Its brilliant orange tentacles arranged in twin whorls made for excellent photos.
And last but not least, a friend showed me another of my target species: a black starry urchin (Arbacia stellata). A recent storm had killed and washed up many of these urchins, but a couple remained on the pier piles. The tide had risen so much that I had to wade almost up to my waist to see it. This species has longer spines than the typical red and purple urchins we see on exposed coasts. Plus this was a new species to me, like many of the other animals we saw that day, and I was stoked to find one in the wild.
It was just before 8 am when we decided we were tired and it was time to leave. We had seen a ton and were well rewarded for getting up a 4 am to do so. But several of us still joked that we would be going back to bed upon getting home.
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