One of the many delightful animals in the rocky intertidal is the vermetid snail, Thylacodes squamigerus. Unlike their more typical gastropod relations, the vermetids don't live in a shell, per se. Instead, they live in a calcareous tube, which forms a loose coil draped over the surface of a rock. The tubes can be up to about 12 mm in diameter, and, if straightened out, about 15 cm long. In some locations, Thylacodes can be very abundant. In a recent visit to Point Pinos in Pacific Grove, I saw many of them in the low intertidal. I occasionally see them on the northern end of Monterey Bay and points farther north, but at nowhere near the abundance I see in Pacific Grove. At a larger scale, iNaturalist shows observations of T. squamigerus from northern British Columbia down to southern Mexico.
Most snails are either grazers (e.g., abalones, limpets, turban snails) or predators (e.g., whelks, conchs, cone snails). Thylacodes is a bit of an outlier with regards to feeding as well as housing, for it is a suspension feeder. Being entirely sessile, it cannot go out and forage. And unlike its doppelganger, the tubeworms Serpula columbiana and S. vermicularis, Thylacodes does not create a water current to catch food on ciliated tentacles. Instead, it spins threads of sticky mucus that thrash around in the current and capture suspended detritus. When the tide is out the snail hunkers down in its tube, same as any worm. It cannot feed unless it is immersed. Where the worms live in the low intertidal on exposed rocky coasts, the water is moving constantly, and it requires relatively little energy for Thylacodes to feed the way it does. As a bonus, even the calories expended in producing the mucus are recouped, as the snail ingests the mucus strands as well as the food particles they capture.
When the tide came back, I got to watch Thylacodes in action. At Point Pinos there are some areas that form lovely tidepools, deep enough for animals to react to the return of the water and clear enough to make photography and videography possible. So standing knee-deep in a pool I stuck the camera underwater and hoped for the best. And I got lucky—you can see the mucus threads!
And not only that, but I captured some video footage. I use a point-and-shoot for these underwater shots, and usually don't know what or whether I've shot anything good until I download images and video at home. Color me happy to have seen these clips!
Despite the unusual aspects of its biology, Thylacodes is indeed a snail. It has a conventional snail's radula, and uses it the way, say, an owl limpet (Lottia gigantea) uses hers to scrape algae off rocks at Natural Bridges. Only instead of scraping the radula against rocks, Thylacodes uses its radula to reel in the detritus-laden mucus threads. That's what's going on in the second video clip above.
So there you have it, another of my favorite animals. Thylacodes is one of those animals that doesn't look like much when you see it just sitting there. But we get to see it only during the tiny fraction of its life that it spends emersed. As with most inhabitants of the rocky intertidal, much of Thylacodes' life occurs out of sight for human eyes. This makes the occasional sighting of Thylacodes under water especially enlightening. And delightful!
Last week we had some of the best low tides of the season, and I was grateful to spend three consecutive mornings in the intertidal. The picture-taking conditions were fantastic when I went to Natural Bridges, and I snapped away like a madwoman. Unfortunately, last week was also finals week, and it wasn't until I got all of the grading done and actual grades submitted that I let myself look at the photos. And there were a lot of good ones!
There are many wonderful things about the early morning low tides. One of the best is that most people prefer to remain in bed rather than get up before the sun and splash around in cold water. The past several weeks had been very busy, with little time for solitude, and I badly needed some time by myself in nature.
Usually when I post an entry here I have a story to tell. This time I don't, unless the photos themselves tell the story. Let me know what you think.
Even in the sand, the algae were abundant and conspicuous. In the low intertidal the most prominent algae are the kelps. Here the feather boa kelp (Egregia menziesii) and the various Laminaria species are doing really well. Egregia also occurs higher in the intertidal, but Laminaria and Macrocystis (just visible along the right edge) are low intertidal and subtidal species.
My absolute favorite sighting of the morning was this group of algae on top of the sand. I love the way that the algae are splayed out. They are just so pretty!
Macrocystis pyrifera is justifiably well known as the major canopy-forming kelp along our coast. But it does occur in the low intertidal, as mentioned above.
And now to focus on some individual organisms. Starting with my favorites, the anemones. This time it was the giant green anemone, Anthopleura xanthogrammica, that was the star of the show.
There was a clingfish (Gobiesox meandricus), in its usual under-rock habitat. Don't worry, I made sure to carefully replace the rock as I found it. This fish was about 10cm long. It may be the first clingfish I've ever seen at Natural Bridges. Clearly, I need to do more rock flipping.
A clingfish's pelvic fins are fused together and modified to form a suction cup on the ventral surface. Clingfish can hop around a bit and are super cute when they eat. They sort of dart forward and land on the food, then shuffle around as they ingest it.
The coralline algae were both abundant and flourishing. They are looking fantastic this season. Someday I'll study up on the coralline algae and write about them. For now, here are some happy snaps of Bossiella.
Sticking with the pink theme, another oft-overlooked organism is the barnacle Tetraclita rubescens. It has a few common names, including pink volcano barnacle and thatched barnacle. It is the largest of the intertidal barnacles along the California coast, and can be fairly abundant in some places. It is never as abundant as the smaller white (Balanus glandula) and gray/brown (Chthamalus dalli/fissus) barnacles, though.
Which brings us to my favorite color, purple. The tentacles of the sandcastle worm, Phragmatopoma californica, are a beautiful shade of purple. You don't get to see the tentacles unless the worm is under water, and with the tide as low as it was when I was there this past week, it wasn't easy finding any Phragmatopoma that were submerged. I've written about Phragmatopoma before, so won't go into details here. But look at all those fecal pellets!
And last but not least, here are a couple of the many purple urchins (Strongylocentrotus purpuratus) out there. At Natural Bridges there's a large pool fairly high in the mid-intertidal that is called the Urchin Pool because it contains dozens (hundreds?) of urchins. Most of them are burrowed into the soft rock. Those are sort of easy pickings. I like finding urchins in less-obvious places, like these.
Urchins in the intertidal often cover themselves with bits of shell, small pebbles, and algae. This helps them retain water as the tide recedes. At a location where the rock is soft, such as Natural Bridges, many of the urchins have grown larger than the opening to their burrow and cannot leave to forage; these imprisoned urchins have to wait for pieces of algae to drift nearby, which they can grab with their tube feet and then transport to the mouth on the underside. So long as they don't get pried out by otters, the urchins seem to do just fine.
I think that's enough for now. I hope these photos give you some idea of what it was like out there a week and a half ago. The next excellent low tide series is in mid-June. Snapshot Cal Coast will be in full swing then, so get out there if you can!
For the final field trip of the quarter for Introduction to Field Research and Conservation, I took the class to the Landels-Hill Big Creek Reserve. Located in the Santa Lucia Mountains south of Big Sur, Big Creek was the fourth of the UCSC Natural Reserves we visited this quarter. The site is rugged and spectacular, and because it's not open to the public we were the only visitors there. There's something truly special about arriving at a campsite after dark (which most of us did) and waking up to find that you've landed in paradise. And realizing that you haven't pitched your tent in poison oak!
Saturday 07 May 2022
We had about a day and a half at Big Creek. Saturday we went on a hike that was much longer and more grueling than the gentle saunter I had promised the students. If I get to teach this class again and return to Big Creek, I now have better plans for how to manage things. We did hike through areas that burned in the Dolan fire in 2020, and were able to see first-hand now the landscape is recovering from that disturbance.
First, some facts about the Dolan Fire. It was started in the Los Padres National Forest in August 2020 by a man who was convicted of arson, throwing rocks at a vehicle, cultivating marijuana on public lands, and 12 counts of animal cruelty; this man, whose name shall go unmentioned here, was sentenced to 24 years in prison just a few days ago. The fire burned over 124,000 acres, cost the state $63 million to fight, destroyed 10 residences and four other structures, and damaged nesting sites for California condors, resulting in the deaths of 12 of the endangered birds. One of the casualties of the fire was the outhouse at the Redwood Camp campground, which is where we were camping. The outhouse had been rebuilt recently and was brand spanking new when we arrived.
Yes, it's a lovely outhouse, but I really took this photo to show the burnt trees. Redwood Camp is situated alongside Devils Creek, in the redwood forest. The fire came right down to the road and scorched trees along the canyon wall. Many dead trees had to be removed and trails cleared before Big Creek could reopen.
Our hike-that-was-more-than-a-saunter took us up the fire road to Whale Point, where we had spectacular views of the Santa Lucia Mountains in one direction and the Pacific Ocean in the other. Along the fire road our guide showed us fire damage to the redwood forest, and pointed out signs of recovery.
Redwoods are adapted for fire. They have a thick bark that shields the inner living tissue from damage, so long as the fire isn't too hot. The outermost layer of bark is frizzy and burns really fast, so a redwood on fire blazes like a match catching for a few seconds, then goes out. Old redwoods have few, if any, branches near the ground, so a low temperature fire at ground level would cause very little damage to a healthy tree. Fire clears out the underbrush and opens up the canopy, creating an opportunity for some young sapling to reach for the light. Fire suppression, on the other hand, allowed the accumulation of several decades' worth of vegetation, and when the Dolan Fire came through it burned hot and furious.
I knew, of course, that redwood trees are clonal. They sprout new trees from the roots and can eventually form "fairy rings". These occur when a mother tree puts up a ring of clonal offspring. Eventually the mother dies, leaving a ring of trees surrounding either a stump or an open space. We see in the Santa Cruz redwoods all the time.
What I didn't know, but learned at Big Creek, was that redwoods also have epicormic growth, in which new shoots originate from the beneath the bark of the tree, sometimes halfway up the trunk.
Epicormic buds lie dormant underneath the bark layer, their growth suppressed by hormones released by active shoots higher up in the tree. When those higher shoots are damaged, the cessation of hormones allows the epicormic buds to begin growing. The selective advantage of sprouting new growth halfway up the tree is that the new shoots have less far to grow to reach the sun. With redwoods being so tall, an epicormic bud located halfway up the trunk has a major leg up on the competition trying to grow from ground level.
However, that doesn't mean that many trees damaged by fire don't grow from roots. We saw lots of those, too. Our guide said that post-Dolan some redwoods grew from root sprouts and some from epicormic buds, and that there wasn't really any rhyme or reason as to which trees did which.
These young trees sprouted in 2021, a few months after the Dolan Fire was extinguished on 31 December 2020. The first year's growth is the dark green color. The new growth added in 2022 is the brighter and paler green. Here's another young tree where the color between the 2021 and 2022 growth is more striking:
After breakfast on Sunday the students packed lunches and dispersed to work on their rapid research projects (RRPs). The RRP is a field exercise in which students devise an entire research project, from initial observations and questions to final presentation, in a few hours. I've found it to be a very effective assignment, because it forces students to simplify and narrow their ideas. They simply can't get too carried away if they have to make a poster and present it to their classmates in half a day. When students are working on RRPs my job is to keep them focused and on-task. Sometimes this is easier said than done. We had students working in the forest, in the creek, and on the beach.
At Big Creek there's a new classroom built down by the beach. No matter where the students did their actual research, we would all meet at the classroom to build and present posters.
It's hard to see in the photo, but to the right of the middle of the building, in the corner of the ell, there's a glass door. Directly across on the opposite side of the building there's another glass door, so you can see all the way through the building. We discovered that this is a problem, as two birds had tried to pass through the building and smacked into the glass. They were both dead. So on the spur of the moment I turned it into an impromptu lesson.
I couldn't ID either bird off the top of my head, so a handful of students and I sat down with the birds and some field guides to study bird anatomy and identification.
We talked about different types of feathers—primary and secondary flight feathers, coverts, tails—and their functions. After working through descriptions in the field guides I was pretty certain that the larger bird was a Swainson's thrush (Catharus ustulatus) and the little yellow bird was some sort of warbler. It was a good lesson for the students, because we looked at physical descriptions and geographic ranges, and could not come up with a definitive answer. I took several pictures of both and uploaded them to iNaturalist when we got home. We were correct about the brown bird, and the little yellow one ended up being an orange-crowned warbler (Leiothlypis celata).
The RRPs were the last part of the field trip, and after that we packed up and headed out. The students went straight back up the coast to get home, and saw three California condors from the highway. Alex and I drove back up to Whale Point where it was really windy, just to see condors, and didn't see any. Go figure. At least I had my camera with me and could take real pictures. And it was another beautiful day.
Last night, 15 May 2022, there was a total lunar eclipse, which turned the full moon dark red. By the time the moon rose above the trees to the east the red phase was in full swing. I learned that it's extremely difficult to photograph what is essentially the new moon against the night sky.
I had better success once the moon started moving out of Earth's shadow and re-learned how to create photo montages. Some day I will remember how to do that and not have to learn it all over again. But the result is pretty nice!
It feels like forever since I've checked in on the cormorants at Natural Bridges. I simply haven't had time to mosey down there, take a gajillion photos, and then deal with them on the computer. But today I thought I'd give myself until lunch time to play with photos and such, before I hit the grindstone again and work on a lecture about the natural history of Big Sur.
And for the update: The Brandt's cormorants (Urile penicillatus) chicks are growing up! They're still mostly fluffy but some have a few feathers, and they're getting big now. I watched for about half an hour before realizing that the parents were feeding them; after that it was pretty easy to see when a feeding was imminent.
First, there's the behavior of the chick(s). Most of the time they are flopped like sacks of brown fluff, but when there's possible food they perk up and pay attention. It's funny how long their necks can be when stretched up! The chicks don't seem able to hold their heads up for very long yet. As we all know, however, food is a powerful motivator.
The parent also demonstrates what I think of as an about-to-regurgitate movements. It sort of reminds me of the cats' convulsions right before they hork up a hairball, only not as fast or violent. The parent cormorant stands up and sort of undulates front to back a few times, then bows low. This gets the chicks' attention and they start looking alert and expectant. The parent might go through the whole routine a few times before leaning towards the chick. The chick begins poking at the parent's bill, which seems to stimulate the actual regurgitation. Nom nom nom!
What I want to showcase this time is a series of photos showing a feeding session. The whole thing took about five seconds.
Look at those stubby little wings! These youngsters have some growing to do and have to make real feathers before they can fledge. Maybe they'll have done so by the time I finish up with school for the year.
One of the things that I've been doing with my Ecology class since almost the very beginning is LiMPETS monitoring in the rocky intertidal. Usually we have a classroom training session before meeting in the field to do the actual work. This year we are teaching the class in a hybrid mode, with lecture material being delivered remotely, so we don't have class meetings except for our field trips. The LiMPETS coordinator for the Monterey Bay region, Hannah, and I arranged to meet at our sampling site, where she would do a training session on the beach before we herded everyone out into the intertidal. It truly was a great plan! But the weather intervened and a spring storm blew through, bringing in a big swell. There was a high surf warning for our area the day of our scheduled LiMPETS work. Hannah and I conferred via email and decided that we'd still give it a shot, and at least the students would have an opportunity to learn about the LiMPETS program and practice with the datasheets and gear.
I arrived early to see how the surf was looking, and it was impressive. The waves were regularly covering our sampling location with whitewash, even as the tide was going out. When my co-instructor arrived and I showed him where the transect would lie, it was an easy decision to make to cancel the monitoring. But we would still be able to do the practice stuff, so we convened with Hannah on the bluff and she went into teacher mode.
We didn't bother with the transect, but had groups of students work through some quadrats out on the intertidal bench, which you can just see in the background of the photo above. Hannah kept everyone out of the danger zone and we stressed the importance of having one member of each group keep an eye on the ocean at all times. We stayed mostly in the high zone, venturing down into the upper mid zone only when the tide was at its lowest. Even then, the big swells would surge up the channels and splash up onto the benches. Nobody got swept off, though, or even more than a teensy bit damp.
Most of the students left after what little work we had for them to do, and that gave me the freedom to poke around on my own and take pictures. I hadn't had a chance to do this in a long time, and intended to make the most of a decent low tide that was almost wiped out by huge swell.
The water was pretty murky, so not great for underwater photography. Some of the shots turned out pretty well, though. The soft pale purple structures that you see in the photo below are papullae, used for gas exchange. You can see these only when the star is immersed.
A couple of students stayed after the rest of the class had left. They were happy to see the nice fat ochre stars, and so many of them in one small area.
It's always good to see so many big ochre stars. For this species, in the intertidal areas that I visit, sea star wasting syndrome (SSWS) no longer seems to be a problem. Fingers crossed! We'll have to see what unfolds in the next months and years.
This week was my spring break, and although I have more than enough work to catch up on, I decided that each day I would spend a few hours doing something fun before or after getting stuck in with adult responsibilities. I didn't set up formal plans, but knew I wanted to collect a plankton sample early in the week. Monday 21 March 2022 was the vernal equinox, which seemed as good a time as any to see what was going on in the plankton.
And the plankton was quite lively! I was very pleased to see a lot of diatoms in the sample. Diatoms are early season bloomers, able to take advantage of nutrient inputs due to coastal upwelling. They are usually the most abundant phytoplankters from about March through July.
All of those button-like round objects are centric diatoms in the genus Coscinodiscus. They can be large cells, getting up to 500 μm in diameter. Coscinodiscus is in some ways the quintessential centric diatom, as you will see below.
Take a look at these objects:
Clearly, one is a circle and one is a rectangle, right? Well, yes, but these two objects are the same type of thing—they are both cells of Coscinodiscus. The easiest way to understand diatom anatomy is to think of the frustule (the outer skeleton of the cell) of Coscinodiscus as being constructed like a petri dish. Because that's actually what it is: an outer casing of silica with two halves, one of which fits over the other exactly the way a petri dish lid fits over the bottom of the petri dish. If you place a petri dish on a table and look down on it, you will see a circle. But if you pick up the petri dish and look at it from a side view, you will see a rectangle. If you don't believe me, go ahead and try it with any canned food item in your pantry. Coscinodiscus is the same. If it lands on the microscope slide lying flat, it will look like a circle; this is called the valve view because you are looking down on the surface of one of the two valves of the frustule. Most of time when we see Coscinodiscus we see it in valve view. Sometimes you get lucky and a cell remains "standing up" even after you drop a cover slip on top of your sample, and you see the cell as a rectangle. This is called the girdle view. So in the photo above, what you see on the left is a Coscinodiscus cell in valve view, and what you see on the right is the same type of cell in girdle view. Same object, two perspectives, and two shapes. By the way, this is the answer to the question posed in the previous post.
And this is what a valve view of Coscinodiscus looks like when you zoom in:
You can see some of the sculpturing on the frustule, and the beautiful golden-brown color of diatoms. The diatoms are related to the brown algae and share the same overall set of photosynthetic pigments, which explains why diatoms are often the same colors as kelps.
Another of the common diatoms around here are those in the genus Chaetoceros. The prefix 'chaet-' means 'bristle', and the cells of Chaetoceros have long bristles. Unlike Coscinodiscus, Chaetoceros forms chains. Some species form straight chains, others form spiraling chains, and still others form a sort of meandering chain that is embedded in a tiny blob of mucilage. The cells below are forming a straight chain.
In addition to all of the diatoms, there were more dinoflagellates than I expected to see. Ceratium was very well represented, often in chains of two cells.
I was even able to capture some video of Ceratium cells swimming in the thin film of water under the coverslip. Dinoflagellates have two flagella: one wrapped in that groove, or "waistline", and one that trails free. Usually it's the trailing flagellum that's easier to see, and if you watch you'll be able to see it in each of the cells.
Protoperidinium was another common dinoflagellate in the sample. Unlike the diatoms and photoautotrophic dinoflagellates, which have that sort of golden-brown color, Protoperidinium is a heterotroph. It eats other unicellular protists by extruding its cytoplasm out of the holes in its cellulose skeletal plates and engulfing prey, similar to the way an amoeba feeds. Because it does not rely on photosynthesis for obtaining fixed carbon, Protoperidinium comes in colors that we typically don't associate with photoautotrophs. Pink, red, and grayish brown are common colors. This time I saw several that were bright red.
So that's a glimpse of springtime in the ocean. Now let's look up!
Legend has it that the swallows return to San Juan Capistrano every year on March 19, which is St. Joseph's day. I don't pay attention to St. Joseph's day, but I do pay attention to the vernal equinox every year and keep an eye out for the return of our swallows to the marine lab. We get both cliff swallows (Petrochelidon pyrrhonota) and barn swallows (Hirundo rustica) building mud nests on our buildings. Last year (2021) the cliff swallows showed up first, with the barn swallows arriving a few weeks later; I remember being worried that they might not show up at all.
This year the swallows returned right on schedule. I saw my first barn swallows on the day of the vernal equinox, 21 March 2022.
They are so pretty! I haven't seen any nest-building yet, but did witness what might have been a territorial spat. The bird in the photo above is the one on the left that is retreating in the photo below
Look at that gorgeous outspread tail! Barn swallows migrate to North America from southern Mexico and Central America. The cliff swallows come all the way from South America; no wonder they're a little late arriving in California! I think they'll show up any day now, and both they and the barn swallows will begin daubing mud above doorways and under the eaves.
Somehow, no matter what else is going on and what the calendar says, it never feels like spring until the swallows are zooming around again. Spring is my favorite season, as there's so much going on, and I begin to feel energized again with the longer days. I have a busy spring teaching schedule and don't know how much time I'll have to do fun things like look at plankton for the hell of it, but will try to slow down often enough to take note of what's happening around me.
For the second year in a row (that I am aware of, anyway), the Brandt's cormorants (Urile penicillatus) have claimed the last remaining arch at Natural Bridges as a breeding rookery. I remember being so excited at "discovering" them in 2021. Anyway, they're back again, building piles of algae into nests.
BTW, if you're keeping score at home, the genus name for the North Pacific cormorants has been changed from Phalacrocorax to Urile. A 2014 study showed this North Pacific group to be a sister clade to those in the genus Phalacrocorax, and in 2021 the International Ornithologists' Union formally adopted the genus Urile for them.
During the breeding season the Brandt's cormorants develop long, wispy white plumes on the cheeks and in two smaller tufts over the shoulder blades. In my head I've been calling them Einstein plumes because although they probably do have a real name, I don't know what it is. When you see a face portrait of one of these birds, you'll know what I mean.
The color blue also features in the breeding phenotype of Brandt's cormorants. Cormorants are related to pelicans, which of course have that huge gular pouch that can hold gallons of water. The gular pouch of cormorants isn't nearly as large. For the Brandt's cormorants, the blue gular pouch indicates sexual maturity. And can you see the color of the eye of the bird that is bowing? The eye of a sexually mature bird turns a brilliant cobalt blue during the breeding season. Brandt's cormorants nest on rocks or cliffs, with the male gathering most of the nesting material. At Natural Bridges, the nests are made up mostly of algae, but I've seen a few birds flying by with surfgrass in their mouths. This male above has brought back a nice clump of red algae (a species of Cryptopleura, maybe?) to an appreciative mate.
So those are the Brandt's cormorants.
This year there is a second species of cormorant hanging out on the sides of the rock. These are pelagic cormorants (Urile pelagicus).
I first noticed the pelagic cormorants early in March. I saw those white patches on the flanks and thought, "But that's not the right body shape for a pigeon guillemot!" I came home, looked them up, and sure enough, they are pelagic cormorants. The pelagic is a little smaller and more slender than the Brandt's, and has a red face and glossy black-green plumage with the white rump patches during the breeding season. These three pelagic cormorants are on small ledges on the side of the same rock where the Brandt's cormorants are nesting, providing a nice demonstration of resource partitioning.
So, are these pelagic cormorants really the new kids on the rock? Going by my photographs from 2021, I'd say yes. I looked back through the photos I took when I discovered the Brandt's cormorants, and did not see pelagic cormorants in any of them. Of course, absence of evidence is not necessarily evidence of absence, and it could very well be that the pelagics have been there all along with the Brandt's and I simply never noticed them. Given that my area of expertise is absolutely not birds, I'm quite prepared to learn that I am wrong about this. But the pelagic cormorants are new to me, and that's reason enough to be delighted by them.
Date/time: Saturday 2022-02-19, 08:00-09:30 Location: Natural Bridges State Park Weather: Chilly (8.3C), as sun hadn't yet risen above the roofs of the houses nearby; very light breeze
For Day 2 of the 2022 Great Backyard Bird Count (GBBC) I went to Natural Bridges, not suspecting that I would be able to ID and count so many species literally just inside the park boundaries. I ended up dividing my observation period into three locations and spent about half an hour at each.
Observation spot #1: Just inside the park boundary on Delaware Avenue (see map below)
