Sometimes dead things can be very informative. Not in the same way as their living counterparts, of course, but there are times when observing a dead specimen reveals details that cannot easily be discerned when the creature is alive. For example, most living birds don't let you get a close look at their feet. Dead birds, on the other hand, don't complain and try to maim you when you spread their toes and look for webbing. What does webbing have to do with anything? It tells you whether and how a bird swims, of course.
Cormorants are fish-eating predators. Like their relatives, pelicans, they do plunge-dive from the air into the water. However, cormorants are much more streamlined than pelicans and also chase their prey underwater. A bird locomoting in water has two options for propulsion--it can use its wings to "fly" underwater or use its feet to paddle along.
Take a look at the foot on that dead cormorant. It is clearly webbed, eminently suitable for a bird that uses its feet to swim underwater. The location of the feet also has functional significance. Note how far back they are on the bird's body. Obviously this helps increase the overall streamlining of the body. Now think about how submarines move through water: the prop of a submarine is also positioned on the back of the boat. That's probably not a coincidence.
Any trip to the beach brings opportunities to see creatures that have washed up. Or are in the process of washing up. Sometimes even (relatively) large animals end up beached. The big scyphozoan medusae, for example, have little control over where the currents take them, and find themselves in shallow water close to shore.
Animals made of jelly do not fare well when they encounter land. There were several of these dinner-plate-sized jellies drifting and pulsing lazily in very shallow water. A few had been left stranded by the receding tide and were already drying up. Even the ones that were still alive would probably never get back to deeper water. Fortunately for them, they are blissfully unaware of their imminent demise--sometimes lacking a centralized nervous system with its all-knowing brain would be a blessing.
Death, of course, is a part of life and a very important part of nature. Even knowing that, it can be disturbing to see dead animals washed up on the beach. For most people, the shells and whatnot of invertebrates don't seem to count as dead things, but everybody recognizes a dead bird. And there is a natural human tendency to feel sorrier for things that are more like us. From a biologist's perspective, keeping track of dead animals on beaches can give us a lot of information about conditions in the sea. There is a sort of standard death rate, but deviations above what is considered normal may signify that something is going on. There are volunteers who make monthly patrols along beaches in the Monterey Bay Area, collecting data on the various carcasses that wash up. These data are used to evaluate the overall health of the waters within the Monterey Bay National Marine Sanctuary. Knowing about dead things can teach us about what's going on with the living things.
This time of year is when California earns its nickname as the Golden State. It isn't only the dried vegetation blanketing the hillsides. The light itself takes on a golden hue, especially in the morning and evening when the sun is low on the horizon. Photographers call the time periods just after sunrise and just before sunset the 'golden hour' and with good reason. Some of my favorite photos were taken in either the early morning or late evening.
Today the Elkhorn Slough National Estuarine Research Reserve (ESNERR) held an open house event. Booths were set up on the field outside the visitor center, with information on native plants, research projects taking place at the slough, a watershed demonstration, mosquito abatement tactics, face painting for kids, and even a food truck. I hadn't been to the slough since early summer, and when I got the notice about the open house I decided to spend the morning there. I'd hike around a bit, take some pictures, and do some nature journaling.
It certainly was a beautiful morning. It had been swelteringly hot earlier in the week, and fortunately the heat had lessened. There was a strong cool breeze and the sky was a clear blue.
In the spring, when I bring my Ecology students to the slough, the landscape is green. The grasses are green and wildflowers are in bloom. Even the pickleweed looks nice and fresh in the spring. Six months later, however, those same grasses are brittle and brown, and most of the wildflowers have long gone to seed and senesced. The live oaks retain their foliage throughout the year, and after two successive wet winters they are lush and green.
When I arrived at the reserve this morning I spent a few minutes touching base with acquaintances and meeting some new people, then wandered off on one of the trails. It was a little chilly, very welcome after the previous heatwaves, and I sat on a bench to do some painting and looking around. After about half an hour I heard something behind me that didn't sound like the wind blowing through the grasses. It was much more rhythmic and regular--definitely some critter walking through the brush. Very quietly, I stood up and sneaked around the oak tree to see a group of three or four juvenile wild turkeys disappearing into a thicket.
All in all I had a pretty good two hours of bird watching. I don't consider myself a birder, really. I enjoy watching birds, just like I enjoy watching other animals. The competitive aspect of birding is a real turn-off for me. I don't care about keeping a life list and comparing it to anybody else's. That said, I do like to keep note of what I see at a given time and place, because it helps me understand the natural world a little better. For example, the other day I heard my first golden-crowned sparrow of the season, and although I haven't seen it yet, knowing it is there makes me think that autumn has truly arrived.
In past decades, several different groups of people have been working to restore natural habitat to the slough. One of the earlier ideas was to build artificial islands, hoping they would encourage the marsh plants such as pickleweed to recruit and expand to their former abundance. It didn't really work, but the islands do provide places for resident and migratory birds to stop and rest.
More recently, a consortium of stakeholders has worked to restore marshlands closer to the ocean. They filled in areas that had been completely flooded, and pickleweed recruited there on its own. That area has been restored to a much more natural condition, with meandering waterways and pickleweed that isn't drowned by seawater. Elkhorn Slough falls into several jurisdictions at the federal, state, and local levels, and getting these groups to work together for a common goal can be difficult. The success that they have had speaks to their willingness to cooperate. I think it helps that any actions taken are based on science, rather than politics or economics.
Over the summer, a lot of work was done to eradicate non-native plant species. This work is ongoing, and may very well never be finished, but it is good to the ecosystem to try. An island called Hummingbird Island has been rid of invasive eucalyptus trees, and now the only trees there are native live oaks and cypress. The trail I hiked went through several areas where trees has been cut down.
Remember that train I mentioned? Here it is, traveling through the slough at about midday.
Sometimes visitors to the slough don't believe that those tracks are actually used.
Much of the land that the ESNERR sits on used to be a dairy. These barns are, I think, the only dairy buildings that remain. Visitors aren't allowed into Little Barn, but we can walk through Big Barn. It is used for occasional equipment storage and is inhabited by barn owls. Sometimes we find owl pellets on the ground beneath the owl boxes mounted in the barn. It is also not unusual to find pieces of those old-fashioned glass milk bottles near the trails.
When I was a little kid I disliked autumn because the shortening days meant that summer was over and winter was coming. As I grow older, though, and gain a presumably more mature outlook on life, I am more able to appreciate the glory of autumn. I still think spring is my favorite season of the year, but autumn in California is indeed golden and lovely.
A few weeks ago I was contacted by a woman named Kathleen, who reads this blog and is herself a student of the seaweeds. She said that she studies a site up at Pescadero, about an hour up the coast from me. We decided to meet up during the series of low tides around the Fourth of July so we could explore the area together, and she could help me with my algal IDs. My friend and former student, Lisa, joined us for the fun.
The most prominent landmark along the coastline in this region is Bird Island, which is accessible only at minus tides, when it is revealed to be a peninsula. It smells pretty much as you probably imagine, especially if you happen to be downwind. Given the prevailing wind direction, that means that the closer you get to Bird Island from the south, the stronger the smell. Kathleen's site is the south side of Pescadero Point, fortunately far enough south of Bird Island that the smell isn't noticeable from that distance. She has a permanent transect that she surveys regularly, taking note of algal abundances and distributions.
One of the notable things we all noticed was the conspicuous presence of big, healthy ochre stars (Pisaster ochraceus)--many hand-sized or larger. I also saw many smaller stars, in the 2 cm size range, but these were hidden in crevices or under algae. The big guys and gals, were out there in plain sight.
However, not all was perfect for the sea stars at Pescadero Point. One of the ochre stars showed symptoms of sea star wasting syndrome (SSWS). It had autotomized two of its arms and had a sloppy, goopy open wound that extended into the oral disc. It was also mushy when I touched it and didn't firm up the way healthy stars do. This star is a goner, even though it doesn't know it yet. That's the beauty (and in this case, tragedy) of an entirely decentralized nervous system.
After I mentioned having seen a sick sea star we compared notes on the current status of SSWS. What more do we know about the syndrome, and any recovery of stars? We came to the consensus that the oubreak was probably caused by a perfect storm of ecological conditions--an opportunistically pathogenic virus that is ubiquitous in the environment, environmental stresses, and high population densities both intertidally and subtidally. Kathleen asked me what I had been seeing recently. I told her that Pisaster ochraceus, one of the species that melted away in spectacular fashion, seems to be making a strong comeback in the places where I used to see it in large numbers. Even though every once in a while i see a sick star, places like Natural Bridges and Davenport Landing are again populated by lots of hand-sized-or-bigger ochre stars. Which of course brings up the question of where these large stars suddenly came from. I think they were tiny stars when the outbreak occurred, hiding in the mussel beds. Many of them died, but as with any plague there are always some survivors. Those lucky few managed to hang on and creep into the niches that opened up when so many adults died. But would little juveniles only a few millimeters in diameter be able to grow to the sizes that we're seeing now, in ~5 years? I suppose that's not out of the question, and we know that when fed well in the lab they grow very quickly, but individual growth rates in the field are difficult to measure.
Another animal goody that we saw were clusters of the bryozoan, Flustrellidra corniculata. Unlike most bryozoans, which are calcified and crunchy, Flustrellidra colonies are soft and flexible. They look more like strange, thick pieces of brown algae than anything recognizable as a bryozoan.
We were there to do some basic marine botany, and although I kept getting distracted by the invertebrates I did also pay attention to the floral aspect of Kathleen's site. She pointed out that Laminaria sinclairii, one of the small low-intertidal kelps, was always abundant. It's true, there were rocks that were entirely covered with L. sinclairii, like this one:
Laminaria sinclairii and L. setchellii are the most common intertidal species of the genus on our coast. They are easily distinguishable because L. sinclairii has a single undivided blade arising from the stipe, and L. setchellii has a blade that is subdivided into fingerlike sections; in fact, the former species epithet for L. setchellii was dentigera, referring to 'finger'.
See the difference?
There is a third species of Laminaria on our coast, that I knew only by reputation. What I'd heard is that Laminaria ephemera resembles L. sinclairii except for the morphology of the holdfast: L. ephemera has a discoid, suction-cup holdfast while L. sinclairii has the more typical hapterous holdfast (made of intertwined cylindrical projections). I think I might have seen a few L. ephemera at Pescadero. These thalli appear to have suction-cup holdfasts, don't they?
We didn't spend much time on the south side of the point, but scrambled over the rocks to the north side, where there are stretches of sandy beach between rocky outcrops. Bird Island is that peninsula in the top of the picture. As I mentioned above, it is connected to the beach only at low tide, so while I think of it as a peninsula, it really is an island most of the time.
Once on the north side of the point we slowed down and made some more attentive observations of the flora. It turns out that this portion of our intertidal visit was sponsored by the letter 'P'. One of the things we all noticed was the prevalence of Pyropia, the filmy red alga that is common in the high-mid intertidal. The thallus of Pyropia consists of a single layer of cells connected to form a very thin elastic tissue. It dries to a crisp in the sun, but rehydrates when the tide returns. You've probably encountered Pyropia before without realizing it: nori is made of Pyropia that has been shredded and processed into paper-like sheets, used for things like sushi rolls.
Although it looks uniformly blackish-green when packaged for human consumption, Pyropia's color in life is a glorious iridescent mixture of greens, olives, and purples. It is another of those easily overlooked denizens of the intertidal that deserves a much closer look than it usually gets.
Another common red alga at Pescadero Point is the delicate and lacy Plocamium cartilagineum. This is one of the hobbyist phycologist's favorite species because it presses like a dream and makes great gifts or wall decorations. As I wrote about here, Plocamium has a doppelganger: Microcladia coulteri. These algae share a similar morphology, but as I mentioned in the previous post, natural history makes it easy to distinguish between the two in the field. Microcladia is epiphytic, growing on other algae, and Plocamium is not.
Plocamium grows on rock surfaces in the mid-to-low tide regions. It sometimes gets surrounded or even buried in sand, but if you dig down far enough you'll always find the holdfast attached to a rock (or shell or other hard object).
Last month I wrote about Postelsia palmaeformis, the sea palm. We found a most handsome specimen washed up on the beach. Note that, as per usual, it wasn't the holdfast of the kelp that failed. The holdfast did its job perfectly well, and it was the mussel it was attached to that broke free of the rock.
The sad thing about finding great specimens like this on the beach is the realization that it will soon be dead. In fact, so will the mussel. Such is the price organisms pay for failing to hang onto their substrate (or for their substrate's failure to hang on). The rocky intertidal is a harsh place to live, and can be unforgiving of mistakes and bad decisions.
That's part of the reason I find it so fascinating. Most wild organisms live on the knife-edge of survival, with only the thinnest margin between life and death. Every organism has its predators, pathogens, and parasites to deal with on a daily basis, in addition to the physical stresses of its habitat. All of the organisms that I study in the intertidal are marine--not freshwater or even brackish, although some can tolerate reduced salinity (and on the other extreme, some tolerate very high salinity). They evolved to live in the ocean, in a habitat where the ocean abandons them for a few hours twice a day. Yet as improbable as that sounds, the diversity in the intertidal is astonishingly high. Obviously, for those that can live there, the trade-off between stability and safety is worthwhile. Nature will always find a way.
The annual Snapshot Cal Coast period is scheduled to coincide with the best midsummer low tides, to maximize opportunities for people to get out and blitz the intertidal. The whole idea of Snapshot Cal Coast is to document as much biodiversity as possible, to render a comprehensive account of what our coastal and nearshore biota look like at this moment in time. For someone like me, participating in the various bioblitzes that occur during Snapshot is a good excuse to get up early and play in some of my favorite intertidal sites.
We're in the high summer growing season now, and the algae are taking off. Pigeon Point has always been a great spot for seaweed diversity, and I anticipated having a lot much phycological fun when I went there last week. And, very happily, I was not disappointed. There were many animal finds as well, including some nudibranchs that I brought back to the Seymour Center, but the algae were definitely the stars of the show. So I thought I'd show off how beautiful and diverse they are.
The red algae
The vast majority of macroalgae at Pigeon Point are red algae, in the phylum Rhodophyta. Everywhere you look is a sea of rosy pinks, dark purples, and bright or brownish reds, punctuated now and then by a brilliant splash of green which is due to the surfgrass (not an alga!), Phyllospadix. The algae cover all surfaces. They drape into and drift with the water currents. They provide shelter and food for the animals of the intertidal. They make walking a treacherous undertaking--a large part of exploring the intertidal safely is knowing which algae will support your weight and which will dump you on your butt without a moment's hesitation.
At first look, the eye is bombarded with a confounding mélange of reds, dark greens, pinks, and purples. Knowing that they are all in the Rhodophyta doesn't help you make sense of what you are seeing. As usual, what helps is an ability to flip between what I call 'forest' and 'tree' observing: you can spend some time zeroing in on individual specimens and learning or remembering their names, but every once in a while you need to step back and take note of the larger environment where and with whom these species live.
Here's a small forest view to study. How many different red algae can you see?
It's kind of a trick question. A knowledgeable person can probably pick out seven or eight different species. I can distinguish six but can identify only five with any real certainty.
Here's the same photo, with some of the algae labeled for identification:
Species A: Prionitis lanceolata
Species B: Erythrophyllum delesserioides (my favorite alga!)
Species C: either Cryptopleura or Callophyllis
Species D: Neogastroclonium subarticulatum
Species E: Mazzaella splendens
Just because it's my favorite, and is undeniably beautiful, here's another photo of Erythrophyllum:
To give you some idea of the color and morphological variety in the reds, here's a quartet:
Some of the red algae are epiphytic, living on other algae or plants. Epiphytes are not parasitic and obtain their nutrients from the surrounding water. Although they do not drain nutrients from the alga or plant on which they live, epiphytic algae can occur so densely that they shade their host and deprive it of sunlight. In the intertidal, algae in the genus Microcladia grow as epiphytes. I've seen them most often on other reds, but they'll also live on some of the browns. A while back I wrote about how Microcladia closely resembles another red alga, Plocamium, and how one of the ways to tell them apart is to examine the habitat of each. Microcladia is an epiphyte, and Plocamium grows attached to rocks.
This is Microcladia:
You can see the morphology of M. coulteri a little better here, where it is an epiphyte on host with a smoother texture:
The coralline algae are a subset of the red algae. They have a different texture from the other reds, because they deposit calcium carbonate within their cell walls. Corallines can grow as encrusting sheets over surfaces, or have upright branching forms. They are often epizoic (living on animals) or epiphytic.
The brown algae
The brown algae (Phylum Ochrophyta) are not as diverse as the reds, but can be locally abundant. The browns come into their own in the subtidal, where they form the physical structure of California's famous kelp forests. Even in the intertidal they can be among the most conspicuous of the algal flora.
Egregia menziesii, the so-called feather boa kelp, is very common on our coast. It has tough, strap-like stipes that can be 3-4 meters long and a large conical holdfast, so it is pretty conspicuous. Egregia is the most desiccation-tolerant of the kelps around here; it grows as high as the mid-intertidal. The specimen in the photo below looks a little ragged at the ends, which makes me think it might be a holdover from last year.
I've seen Egregia at every rocky intertidal site so far. Other brown algae are more particular about where they live. Dictyoneurum californicum, for example, is a brown alga that lives only in areas that get a lot of water movement. It is seasonally abundant at Pigeon Point, where it is a low intertidal resident, but I don't see it at more sheltered locations such as Davenport or Natural Bridges. This year D. californicum is at Pigeon Point, although not in large patches as it was a few years ago. As the blades mature, they develop a split in the basal region just distal to the short stipe. The blades themselves feel crunchy and brittle.
All that said, the most remarkable brown alga at Pigeon Point has got to be Postelsia palmaeformis, the sea palm.
Postelsia is restricted to the most exposed rocky outcrops, where they bear the full force of the bashing waves as the tide rises and falls. They stick up defiantly above the surrounding topography, as if daring the waves to do their worst.
Sea palms grow to a height of about half a meter, and are usually the tallest things where they live. They typically occur in small clusters. They do resemble miniature palm trees, don't they? It's the thick, very flexible stipe that allows them to live where they do. When the waves come crashing down, the stipe simply bends with the force of the water, and then pops back up after the wave recedes. This hardiness doesn't make the thalli invincible, though. After winter storms blow through, you can often see Postelsia washed up on the beach.
You might think that Postelsia gets ripped off rocks by strong waves, but you'd be wrong. The holdfast for these algae is surprisingly tough and good at doing its job. When you see Postelsia stranded on the beach, you'll usually find that it wasn't the holdfast that gave way--most likely the rock or mussel it was attached to will have been torn off along with the sea palm. That's pretty impressive! Of course, any sea palm washed up on the beach is a dead sea palm, so in that sense it doesn't matter whether it was the alga or the substrate that failed. But given the forces that these algae withstand on a daily basis, it's remarkable how well they manage to hang on in the high energy environment where they thrive.
Algae don't get a lot of love, even among marine biologists. If I think there are not many people who study the invertebrates, there are even fewer who study seaweeds. Some organisms have an easier time attracting the attention of human beings, and among macroscopic organisms the invertebrates and algae are probably tied for the bottom ranking. It amazes me that visitors to the seashore can look over a place like Pigeon Point and not see anything. I suppose it's a matter of getting lost in the forest and forgetting that it is made up of trees, or not even recognizing that it is a forest. In the intertidal the 'trees' are at foot level so it does take some work to figure out what's going on. Like most worthy endeavors, though, the effort is well rewarded.
Professor Emeritus John Pearse has been monitoring intertidal areas in the Monterey Bay region since the early 1970s. Here on the north end of Monterey Bay, he set up two research sites: Opal Cliffs in 1972 and Soquel Point in 1970. These sites are separated by about 975 meters (3200 feet) as the gull flies. My understanding is that the original motivation for studying these sites was to compare the biota at Soquel Point, which had a sewage outfall at the time, with that at Opal Cliffs, which did not. The sewer discharge was relocated in 1976, and the project has now morphed into a study of long-term recovery at the two sites. In the decades since, John has led students, former students, and community members to conduct Critter Counts at these sites during one of the mid-year low tides. Soquel Point is visited on the first day, and Opal Cliffs is visited the following day. When John founded the LiMPETS rocky intertidal monitoring program for teachers and students in the 1990s, the Soquel Point and Opal Cliffs locations were incorporated into the LiMPETS regime.
I have participated in the annual Critter Counts off and on through the years--around here, one takes any chance one gets to venture into the intertidal with John Pearse! I usually have my own plans for this series of low tides, but try to make at least one of the Critter Count mornings. This year (2019) the first 16 days of June have been designated the official time frame for Snapshot Cal Coast, giving marine biologists and marine aficionados an excuse to go to the ocean and make observations for iNaturalist. I had set myself the goal of submitting observations for every day of Snapshot Cal Coast, knowing that every day this week would be devoted to morning low tides. That's the easy part. Next week, when we lose the minus tides, I'll do other things, like look at plankton or photograph seabirds. My plans for this week included a trip to Franklin Point on Wednesday and doing the Critter Count at Opal Cliffs on Thursday. John asked me if I could also do the Wednesday Critter Count. As I alluded above, I'm not going to say "No" to an invitation like that! So I didn't make it out to Franklin Point to document the staurozoans for Snapshot Cal Coast, but that's okay. Some plans are meant to be changed.
Day 1- Soquel Point
Both the Soquel Point and Opal Cliffs sites are flat benches with little vertical topography. The benches are separated by channels that retain water as the tide recedes. The Soquel Point site has deeper channels that make the benches more like islands than connected platforms.
The benches are pretty easy to get around on, as long as you remember that surfgrass (Phyllospadix spp.) is treacherous stuff. The long leaves are slippery and tend to cover pitfalls like unexpected deepish holes. The difficulty at this site is that it takes very little rise in the tide for water in the channels to get deep. You can be working along for a while, then get up to leave and realize that you're surrounded by water. Keeping that caveat in mind, we worked fast.
For the Critter Count we keep tabs on only a subset of the organisms in the intertidal. The quadrat defines our sample; we put it down at randomly determined coordinates within a permanent study area. Some animals, such as anemones, turban snails, and hermit crabs, are counted individually. For other organisms (surfgrass, algae, Phragmatopoma) we count how many of the 25 small squares they appear in. Some quadrats are pretty easy and take little time; others, such as ones that are placed over channels or pools, are more difficult and take much longer.
Because of the rising tide I didn't have a lot of time to look around and take photos of the critters we were counting. Linda and I were worried about finishing our quadrats before the channels got deep enough to flood our boots. But here are two of the things that caught my eye:
Day 2 - Opal Cliffs
The next day we met a half hour later and a few blocks down the road. The Opal Cliffs site is a popular spot with surfers: If you've ever heard of the surf spot Pleasure Point or seen the movie Chasing Mavericks, you know about this location. As far as the intertidal goes, it's an easy site to study. The channels aren't as deep as those at Soquel Point so we could work at a more leisurely pace. As the rest of the group hauled up all the gear and left to get on with their day, I stayed behind to take pictures for my iNaturalist observations. The sky was overcast, making for good picture-taking conditions. I'll just add a gallery of photos to share with you.
There is one critter that deserve more attention here, because I'd never seen one in the intertidal before. Two of the guys finished their quadrats early and started flipping over rocks to look for an octopus. To my knowledge they didn't find any octopuses, but they did find a bizarre fish. At first it didn't look like much:
Hannah, the LiMPETS coordinator for Monterey and Santa Cruz Counties, recognized the fish right away and grabbed it by the body. She held it up so we could see the ventral surface.
This is a plainfin midshipman. These are nearshore fish found in the Eastern Pacific from Alaska to southern Baja. Clearly, I need to spend more time flipping over big rocks! The midshipman is a noctural fish, resting in the sand during the day and venturing out to feed at night. Like many nocturnal animals, it is bioluminescent--those white dots on the fish's belly in the photo above are photophores. Midshipmen are heavily decorated with photophores all over the body. This bioluminescence is used both for predator avoidance and mate choice.
The lives of plainfin midshipmen and human beings intersect in the wee hours of the morning. During breeding season these fish sing or grunt. They breed in intertidal areas, where females lay eggs in nests that are subsequently guarded by males. Both sexes make noise, but it's the breeding males that are the noisiest. They grunt and growl at each other when fighting for territory, but hum when courting females. Females typically grunt only when in conflict with others. People who live in houseboats on the water in Sausalito have reported strange sounds emanating from the water beneath them, only to learn that what they hear are the love and fight songs of fish!
I've always been a fan of the intertidal fishes. They seem to have a lot of personality. Plus, any aquatic animal that lives where the water could dry up once or twice a day deserves my admiration. Of course, all of the invertebrates also fall into this category, which may explain why I find them so fascinating.
After we admired the midshipman's photophores and impressive teeth, we put it back in the sand and replaced the rock on top of it. It was probably happy to get back to snoozing away the next few hours before the tide returned. I don't know how I never realized the midshipmen were in the intertidal. I think I just assumed that they were in deeper water. Now that I know where to find them, I will spend more time flipping over rocks. And who knows, maybe I'll even find an octopus!
If, like me, you are fortunate enough to live near the coast in Northern California, you get to visit the tidepools. And when you do, you may notice something that looks like a pile of sand in the mid tidal zone below the mussel beds. When you venture down and touch the sand, you'll find that it's hard--hard enough to walk on, if you step very carefully, but also somewhat brittle.
It might look something like this:
Meet Phragmatopoma californica, the sandcastle worm. Hard to believe that these mounds, which can be the size of a small dining room table, are constructed by little worms, isn't it? Phragmatopoma is one of the many marine segmented worms grouped together as the Polychaeta. We have lots of polychaetes on our coast, ranging in size from greater-than-hand-length nereids and glycerids that can take a bite out of you and draw blood, to tiny worms small enough to swim in the layer of water between sand grains. In fact, the majority of our worm fauna on the coast consists of polychaetes.
Polychaetes make up a large and very diverse taxon, comprising some 80 or so families. Polychaete taxonomists might argue against it, but to make things simpler, we can divide them into two subclasses, the Errantia and the Sedentaria. As the name implies, the Errantia comprises the worms that are errant, or free-crawling. That said, most of them don't actually crawl around in plain sight; they tend to burrow in sediment, shell debris, or gravel, or wiggle their way through various benthic faunal communities. Some of them make temporary shelters by wrapping themselves in pieces of algae sewn shut with mucus threads. The Sedentaria, on the other hand, are pretty much all, well, sedentary. They live in more or less permanent tubes made of various materials, and generally can't live outside of them.
Phragmatopoma is very much a sedentary worm. It lives in a tube that it builds out of sand grains. Yes, this little worm is a mason!
What you see in these mounds is an aggregation of hundreds of individual worms. The mounds do not form by accident or chance. Phragmatopoma has a planktonic larval stage that floats around on ocean currents for some weeks before returning to the shore. The larva is attracted to areas already colonized by members of their species, which it detects by sniffing out the chemical signal of the glue used to create the tubes (more on that below). This phenomenon is called gregarious settlement. If you consider the challenge of being a tiny creature searching the entire coastline for a place to settle and live forever, one big clue as to the suitability of a given location is the presence of conspecific adults. After all, if your parents' generation grew up there, chances are it's a good spot for you to grow up, too.
Each of those holes in the big sandy mound is the entrance to a worm's tube. Tubes might be as long as 15 cm, but the worm itself is much smaller: a whopping big one would be 4 cm long, and most are in the 2-3 cm size range. From this pair of observations I infer that the worms can and do move up and down the tube. They have to move to the open end of the tube to feed, and can withdraw towards the closed end to avoid predators, or seek protection from desiccation.
Phragmatopoma's tube is not a haphazardly constructed object. It is the worm's home for the entirety of its post-larval life, and is constructed to shield its builder/occupant from the mechanical bashing that occurs twice daily as the tide floods and ebbs. As such, it must be strong and able to maintain its structural integrity. Let's take a closer look at an isolated tube under the dissecting scope:
The tube itself is made of debris--sand grains, bits of shell, the occasional tiny sea urchin spine--that the worm gathers from its environment. Glandular regions at the worm's anterior region secrete around the body a cylinder of sticky cement that is chemically similar to both spider silk and the byssal threads that mussels use to attach themselves to rocks in the intertidal. The inside of the tube is lined with a chitin-like material. The worm uses tentacles on its head region to collect and sort the 'stones' and glues them to the outside of the lining. There is some degree of selection involved; in the photo above you can see that all of the sand grains are more or less the same size, with none standing out as being conspicuously smaller or larger than the others. Growing worms that are actively building their tubes may be geographically restricted at least partly by the availability sand grains of the right size; if the sand is too fine or too coarse, the worm's either can't or don't live there.
Life inside a tube
Living in a tube may provide significant protection from wave bashing and predators, but does present some challenges as well. One thing that comes to mind is the matter of personal hygiene: What happens to the worm's poop? As we know, the worm lives inside the tube but it not attached to it, and can crawl up and down within it. To understand how it does, we have to review some basics of polychaete anatomy.
The word 'polychaete' comes from Greek ('many bristles') and refers to the fact that these segmented worms have chaetae, or bristles, along the left and right sides of the body. In some worms the segments, including chaetae, are pretty much the same from the anterior end of the body to the posterior end. In others, the segments and chaetae are differentiated from one body region to another. In the case of Phragmatopoma, all you can see sticking out of a tube is the head region, consisting of the slender feeding tentacles and a large disc-shaped structure called an operculum, which made of fused cephalic chaetae and serves as a door to close off the tube when the worm withdraws. Behind the head is a collar region, a series of three adjacent segments that have very stiff chaetae that can be pushed out against the lining of the tube to anchor the body in place. The rest of the body behind the collar is the trunk, which bears smaller chaetae on each segment. The entire epidermis is ciliated, which keeps water flowing around the body.
But what about the poop? As in most vermiform animals, Phragmatopoma's anus is at the posterior end of the body, which is oriented towards the closed end of the tube. How, then, does it defecate without fouling its home? The answer is both simple and ingenious. Phragmatopoma has a long rectum, which is curved to run anteriorly back towards the head. The anus, located at the terminal end of the rectum, discharges fecal pellets about halfway up the length of the body. The ciliary currents of the epidermis then flush the fecal pellets the rest of the way up the tube and out the top.
The skinny cylindrical things in the photo below are Phragmatopoma's fecal pellets!
Gas exchange is another challenge for animals that live within tubes. Aquatic animals exchange respiratory gases with the water that surrounds them, which is easy for animals that live where the water is constantly moving over their bodies. But for tube-dwellers, gas exchange is much more difficult. Phragmatopoma has paired gills on each segment of the trunk region of the body, which greatly increase the surface area for gas exchange. Any gas exchange surface is useless unless it connects with the circulatory system, so blood vessels flow into and out of each gill. Dissolved oxygen diffuses from the water into the blood, and is then circulated throughout the body. A certain amount of gas exchange probably occurs across the surface of the tentacles, too. To make things easier, the ciliated epidermis of the body keeps that small amount of water inside the tube moving, minimizing stagnation. When the worm's head is extended out for feeding, the tube is flushed with clean water. When the worm is withdrawn into the tube at low tide, its only oxygen supply is in the water contained in the tube with it. Like most of its intertidal neighbors, Phragmatopoma hunkers down and waits for the tide to return, when it can feed and breathe more easily.
And speaking of feeding, I should mention that Phragmatopoma is a filter feeder. Those purple tentacles are ciliated and create a water current that brings small suspended particles towards the mouth located at the base of the tentacles. In the video below the operculum is the darker object to the left; it represents the dorsal side of the worm's body. The long, filiform tentacles are the feeding tentacles.
As you may imagine, living in a tube also affects the way that Phragmatopoma reproduces. The worms never leave their tubes, so copulation isn't an option for them. Despite their occurrence in large groups they are not clonal, and reproduce only sexually. Both sexes of Phragmatopoma spawn gametes into the water, where fertilization and larval development take place. Living in dense aggregations and spawning at the same time as everyone else maximizes the chance that egg and sperm of the same species will find each other. Many marine invertebrates throughout the oceans, from corals to sea urchins, spawn synchronously. After all, it does an individual no good to throw gametes out into the world if it is the only one of its type around--all of the metabolic energy that went into producing and maintaining the gametes would be entirely wasted.
Clearly, the advantages of living in a tube outweigh the costs and inconveniences. Phragmatopoma has evolved physiological, anatomical, and behavioral adaptations to deal with life in the intertidal. One of those adaptations is the tube, which solves one set of problems but creates others which also need to be solved if the animal is to survive. Evolution comes up with solutions like this all the time. Every trait has metabolic and/or fitness costs, and an organism's biology is based on this type of evolutionary compromise. Life in the intertidal is a tough game. It is probable that none of the various biological processes that keep Phragmatopoma alive work function quite as well as they could, if they were isolated systems. But inside the bodies of these little worms, everything works just well enough for them to be one of the more conspicuous inhabitants of the intertidal.
In my experience, the most difficult organisms to photograph in the wild are staurozoans. Even birds in flight are easier. The problem with staurozoans is where they live. I never see them in calm, still pools, where taking pictures would be easy. Instead, they seem to like surge channels where the water constantly sloshes back and forth, and even in the few seconds between a wave coming in and receding they never really stop moving. Their bodies are extremely soft and squishy, so the slightest current causes them to flutter and make blurry photos. When they are emersed their bodies don't really look like anything except a soggy booger, so they aren't recognizable as staurozoans unless they are underwater. And when underwater they don't hold still, and so on and so forth.
Still, finding them is always a treat, even if I can't capture photographic proof. They really are extremely gorgeous creatures.
They are also enigmatic creatures. Much of staurozoan biology, including their evolutionary relationships, remains poorly understood. Until recently the staurozoans were considered a subgroup of the Scyphozoa, the taxon that includes the large medusae such as moon jellies (Aurelia spp.) and sea nettles (Chrysaora spp.). However, using data from more extensive morphological and molecular studies, most taxonomists now agree that the Staurozoa should be elevated to a level equivalent to the Scyphozoa. In other words, the staurozoan lineage probably evolved alongside, but separate from, the scyphozoan lineage.
Whatever their evolutionary history and relationships, what we know about staurozoans is very limited. They are considered to be stalked jellies (hence their previously assumed close affinity to the scyphozoans) that do not have a separate polyp stage. Their bodies consist of an adhesive peduncle, or stalk, that attaches to algae or surfgrasses, and a calyx or goblet-shaped portion surrounded by eight tapering arms. Each of the eight arms is topped with a puffball of stinging tentaches which are uses to catch food and presumably to defend the animal against predators. The mouth is located in the center of the calyx, usually lifted up on a short stalk called a manubrium. The animal feeds by capturing prey on the tentacles and flexing the arm so the food is brought to the mouth. Staurozoans are not permanently attached and can sort of 'walk' with a somersault-like motion, flipping end-over-end.
Haliclystus 'sanjuanensis' at Franklin Point grows to a length and diameter of ~3 cm, although most of the ones that I see are smaller than that. The most common color is this reddish brown, but I've also seen them in a gorgeous bottle green that makes them much easier to see against the background of their habitat. I usually see them attached to pieces of red algae, but I'm not sure they actually prefer red algae to either green or brown algae. I don't think I've ever seen one attached to a rock.
Last week I had one of those moments in the intertidal when I felt something stuck on my finger and I couldn't get rid of it. That happens frequently, with small bits of algae getting caught on everything; usually I just flick my hand and they go flying off. But this thing wouldn't leave. I finally stuck my hand in the water to rinse it off, and saw that I had been glommed onto by a small staurozoan!
See how the animal stuck to me with its tentacles, while its peduncle is still attached to a piece of Ulva?
As I mentioned, not much is known about these strange animals. They possess the stinging cells to prove their inclusion within the Cnidaria, but are aberrant medusae which stick to algae instead of swimming around in the water column. Their life cycle is more or less cnidarian-like, but their planula is non-ciliated. Their ecological relationships haven't really been studied at all.
Which is why this photograph is so informative. It's not a great picture, by any means, but it shows a glimpse of how staurozoans interact with other species.
This is a picture of two animals, a staurozoan (H. 'sanjuanensis') and a nudibranch (Hermissenda opalescens). Both of these animals are predators. Hermissenda is well known for its affinity for general cnidarian prey, from which it steals the stinging cells to defend its own body (a behavior known as kleptocnidae). But the staurozoan should be quite capable of defending itself. So, who is doing the eating, and who is being eaten?
Given the dastardly nature of Hermissenda, I'd bet on it as the eater. Those damned nudibranchs have to spoil everything! The staurozoan will probably sustain damage, perhaps losing a tuft of tentacles, but should be able to regrow the lost parts. And the sting of the staurozoan may keep the nudibranch from eating as much as it would like. That's the thing. We just don't know.
I'll definitely be keeping an eye out for the staurozoans at Franklin Point the rest of this tide season. I may even bring a few back to the lab for closer inspection; my collecting permit allows me to do so. I could then photograph them under controlled conditions and hopefully get some better pictures. I find these animals very intriguing, being both so clearly cnidarian-like and simultaneously so inscrutable. I always did like a good mystery story!
All semester I've been taking my Ecology students out in the field every Friday. We've visited rivers, forests, natural reserves, endemic habitats, and fish hatcheries--none of which fall into my area of expertise. This year I have several students interested in various aspects of food production, natural/holistic health practices (which sometimes conflict with actual science!), mycology, as well as some who haven't yet decided in which direction to take their academic endeavors. Until very recently I haven't been able to share with my students much of what I really know, which is marine biology. I did have them learn the organisms that live on docks at the harbor, but that was to study the process of ecological succession rather than natural history.
Yesterday, finally, I took the class into my real field, the rocky intertidal. This year it happened that the best Friday to do our annual LiMPETS monitoring was at the end of the semester. We welcomed the new regional LiMPETS coordinator, Hannah, to our classroom on Thursday for some training. Students learned about the history of the LiMPETS program, some natural history of the rocky intertidal in California, and got to practice some organism IDs with photo quadrats of actual intertidal areas.
The real fun, of course, occurs in the field where the organisms live. So we went here:
We didn't have a very good student turnout, unfortunately, but the ones who did show up were diligent workers and we got everything finished that Hannah needed. Most of the time was spent sampling along the permanent vertical transect line. This line is sampled at 3-meter increments along a line that runs from the high intertidal into the low. The same quadrats are sampled every time, and the data collected are used to determine how specific sites change over time. The most difficult part of the monitoring is finding the eye bolts that mark where the transects begin!
I admit, I was a little bummed at the low turnout and late arrival of my students. But the intertidal is the intertidal, and it didn't take long for me to adjust my attitude. I worked up a handful of quadrats with Hannah, then let the students do the bulk of the heavy lifting. This was their field trip, after all. So I wandered around a bit, remaining within hearing distance in case I was needed. I needed to find some stuff!
I just want to show some of the animals and algae in the intertidal yesterday. I didn't realize how much I missed this basic natural history stuff until I got to spend some time simply looking at things.
Such rich life to see! One of the students was astounded when she learned that we could visit sites like this only a few days each month. "At dinnertime today the spot where you're standing will be under several feet of water!" I told her. Mind blown.
Looking more closely, there were, as usual, interesting zonation patterns to observe. One was the restriction of large brown algae to the vertical faces of rocky outcroppings.
In the mid-intertidal, mussels (Mytilus californianus) rule the roost. They are often (but not always) accompanied by gooseneck barnacles (Pollicipes polymerus). The barnacles, for reasons discussed in this earlier post, always live in clumps and are most abundant in the lower half of the mid-intertidal mussel beds.
During the training session on Thursday, Hannah told the students that Pollicipes is easily identifiable because the barnacles look like dragon toes. I think I can sort of see that. They are scaly and strange enough to be dragon toes.
The algae are taking off now, and the site is starting to look very lush.
Even algae start as babies! These balloon-shaped things are young Halosaccion glandiforme thalli, surrounded by other red algae. The large blades belong to Mazzaella flaccida, which makes up a large portion of algal biomass in the mid-intertidal zone.
The tidepools at Davenport Landing are good places to see fish, if you have the patience to sit still for a while and watch. This woolly sculpin (Clinocottus analis) posed nicely in the perfect pool for photography--deep enough to submerge the camera, with clear, still water.
And I was finally able to take a good underwater shot of a turban snail carrying some slipper shells. I've already written about the story of this gastropod trio in case you need a refresher. I'm still waiting to see a taller stack of slipper shells some day.
It was impossible not to feel satisfied after spending some time looking at these creatures. My attitude was mercifully adjusted, and we all departed feeling that we'd done a good morning's work. Our small group of students was able to collect a full set of data for Hannah. That ended up being a very important accomplishment, as Hannah doesn't have any other groups monitoring at Davenport this spring. This means that our data will probably be the only data collected this year at this site. I'm glad the tide and weather conditions allowed us to stay out there as long as we did.
I don't remember what I expected from my first view of Death Valley. I knew it to contain the lowest elevation (Badwater Basin, 282 feet below sea level) in North America and that it was really hot in the summer, but beyond that I had no clue. [Aside: the marine biologist in me wondered which metric 'sea level' refers to, and decided that it was probably mean low low water] I certainly wasn't prepared for the spectacular geology, although in retrospect I shouldn't have been so surprised. We didn't see much in the way of wildflowers, for one reason that I didn't anticipate but which makes perfect sense: although Death Valley received enough winter rain to form a temporary lake in the valley, there hadn't been enough rain in the autumn to trigger a superbloom. That was fine by me, as I'd already seen many wildflowers on the trip and was happy to be fascinated by the geology.
There are at least two small waterways in Death Valley National Park that are called Salt Creek. The first one we encountered was in the hills above the valley, and is a rare desert riparian area.
This Salt Creek is fed by several small natural springs and runoff from the scant winter rains. As you can imagine, this oasis is a vital necessity for wildlife. Animals as large as desert bighorn sheep and as small as quail depend on this water source, which may contain the only somewhat reliable drinking water for 15 square miles.
As I mentioned, for me, Death Valley ended up being all about geology. I knew the valley floor was where we would find the lowest elevation in North America: Badwater Basin, 282 feet (86 m) below sea level. And now I can say that I've seen it, but there isn't much to see except the line of other tourists hiking out across the salt flats to take photos of the sign. So as a must-see destination, Badwater was interesting but not compelling. We skipped it.
But the rocks! The hills surrounding the valley, especially those on the eastern side, are spectacular. My favorite area was a range of hills called Artists Palette, viewable from a gorgeous 1-way loop drive off of Highway 190. When I saw the name on the map I thought it must be a place either a location where painters found minerals they could use to make paint, or a scene they liked to paint. Fortunately we decided to take the detour that meanders through the formations, so we could get off the main road and just gawk. I had never seen anything like this scenery. I know enough geology to understand that minerals come in all sorts of colors, but had not seen them together like this in a natural state. My eye is always drawn to colors, and I couldn't stop goggling at the variety of umbers, ochres, greens, and pinks, all jumbled together like some giant's ice cream sundae.
It's impossible to capture the grandeur of this landscape in a photograph. You really have to see Artists Palette in person to appreciate the vibrant colors of these hills. If you ever go to Death Valley , take the time to drive this little loop. You won't regret it!
Across the valley to the west, are the Panamint mountains. Beyond them, the Owens Valley and the mighty Sierra Nevada!
So those are the rocks. The fish were in the second Salt Creek that we encountered, about 20 miles north of the Artists Drive loop. This Salt Creek is one of the remnant small bodies of water left after Lake Manly dries up. Lake Manly is a temporary lake that occasionally forms in Badwater Basin after unusual heavy rains. Most of the time, though, Badwater Basin is dry except for some small creeks. Salt Creek generally flows from north to south down the valley and eventually disappears into the sand.
Salt Creek is inhabited by a little pupfish, Cyprinidon salinus salinus, that looks like and is about the size of a guppy. Well, maybe it's a little bigger than a guppy. Populations of pupfish inhabit several creeks scattered over the desert across California and Nevada. Over time they have evolved into 10 genetically distinct species and subspecies, each adapted to the nuances of its particular stream. Two of the 10 have gone extinct in historic times. The Salt Creek pupfish, C. salinus salinus, is endangered, due to the ephemeral nature and fragility of its environment.
They are called 'pupfish' because they appear to be playing like puppies. Plus, they are very cute. But life as a fish in one of the driest places on the planet is a tough gig. Pupfish live short, intense lives, growing to adulthood and breeding in the span of a single year.
Salt Creek pupfish (Cyprinidon salinus salinus) in Death Valley
As you can see, the creek is hardly deep enough for these little fish to swim. Pupfish exhibit the sexual dimorphism common in fishes--females are rather drab and nondescript, while males are more colorful. The behavior that was described as playful, earning the fish the moniker 'pupfish', is really all about the business of living. Males are territorial, defending a spot against other males. When a female chooses to spawn with a male, she enters his territory. Then the two of them perform a short, wiggling dance, and spawn together.
From the perspective of an evolutionary biologist, the isolated pupfish populations are fascinating. Each waterway inhabited by pupfish is an independent 'island' in a very real sense of the word. The fish cannot migrate between streams, and thus populations evolve independently of each other. This is called allopatric speciation, from the Greek roots 'allo-' meaning 'other' and '-patry' meaning 'country'. Over time, each population becomes reproductively isolated from the others, so that even if Manly Lake were to become once again a permanent body of water, the fish from different streams would be unable to mate with each other.
Of all the things that manage to eke out a living in what is arguably one of the most inhospitable places in the world, these little fish are my favorite. Major props to them, for surviving where they do and making it look like fun!
Joshua Tree National Park gained a certain notoriety this past winter, when idiots went there during the federal government shutdown and trashed the place. The vandals chopped down the iconic Joshua trees (Yucca brevifolia), let their dogs run around unleashed, left litter scattered over the landscape, and carved new roads through the desert. I'd like to give most people the benefit of the doubt and assume that they didn't realize the damage they were doing to the park. However, it takes only a few bad apples to destroy a public resource for everybody, as we've all experienced at some point.
The very first thing I learned about Joshua Tree is that it has two distinct desert habitats. Hey, I'm a marine biologist, and the desert--any desert--is new territory for me. None of this landscape has been anywhere near the ocean for millions of years! Anyway, the eastern half of the park is Colorado Desert, which is similar to what we had seen at Anza-Borrego State Park. Many of the plants in this region were also familiar to us because we had seen them in Anza-Borrego, but for the most part were more abundant here in Joshua Tree.
For example, we saw many more bluebells (Phacelia campanularia) at Joshua Tree than in Anza-Borrego. The P. campanularia at Joshua Tree also looked healthier (more robust and vigorous, less spindly) than they did in Anza-Borrego. Perhaps the higher elevation of the Colorado Desert in Joshua Tree (approximately 914 meters, or 3000 feet) compared to Anza-Borrego (182 meters, or 597 feet) accounts for this observation.
I really liked the Colorado Desert in Joshua Tree. Even though it was the same ecosystem as what we saw in Anza-Borrego, here the flowers seemed more colorful and striking. The yellows were a little brighter, and the pinks and blues a little deeper. The scenery was breathtaking everywhere I looked. I wish my photos could do justice to the beauty of the landscape.
Aside from the desert bluebells, other flowers that we had seen at Anza-Borrego included the brittlebush (Encelia farinosa), which seems to be ubiquitous in the Colorado Desert. The Arizona lupine (Lupinus arizonicus) was also common in Joshua Tree; like the bluebells, these appeared to be more robust here than in Anza-Borrego.
There were new flowers, too. My favorite, which I didn't see a lot of, was this desert globemallow, Sphaeralcea ambigua:
Here's a close-up of the same plant. Look at that gorgeous orange color!
Against the prevailing palette of yellows and purples, this orange really stood out and caught the eye. This plant is also called the apricot mallow, for obvious reasons.
Some other flowers that we saw:
Among all the colorful flowers in the overall landscape, there was this very subtle plant, easily overlooked by eyes accustomed to more brilliant blossoms.
Something that tickled my funny bone was the little chia plant, Salvia columbariae. It looks like a prickly purple pom-pom. Two days in the desert had taught me not to touch things if I didn't know what they were, but I had to know if these blossoms were as pokey as they looked. They weren't!
There are parasitic plants in the desert, too. The red branches in this bush are the desert mistletoe (Phoradendron californicum), a hemiparasite. It drains water and nutrients from its host plant but performs its own photosynthesis.
In Joshua Tree National Park there's an area called the Cholla Cactus Garden. Chollas are cactuses with cylindrical stems, rather than the flat stems of the beavertail or prickly pear cactuses. The most common one in the Colorado Desert (that we saw, at least) was the teddybear cholla, Cylindropuntia bigelovii. As the name implies, it's a cute, fluffy cactus, but it's definitely still a cactus.
The teddybear cactus blooms in May and June, so we didn't see any flowers. In addition to having the normal plant sex using flowers, these cactuses also reproduce clonally by dropping branches. The dropped pieces roll around and find a new place to attach and grow. Interestingly, this type of clonal replication, called budding, is common in many marine invertebrates!
Here's a newly detached bud from a teddybear cholla:
And here's a recently established, young plant:
Cute little cactus, isn't it?
The trees that give Joshua Tree National Park its name live in the higher and cooler western region of the park, known as the Mojave Desert. The Joshua trees (Yucca brevifolia) live singly or in clusters. In some ways, Y. brevifolia is the symbol of the Mojave Desert. They are also abundant in the higher elevations of the Tehachapi Mountains along Highway 58 between Bakersfield and the town of Mojave.
In Joshua Tree National Park, said trees were blooming in late March.
I'll have more to say about reproduction in Joshua trees and some other desert plants in another post. This one is getting long, and we had more desert adventures to come.