If I asked you to draw a worm and designate the front and back ends, you’d most likely come up with something that looks like this:
And you would be entirely correct. A worm, or any creature described as ‘vermiform’ for that matter, has an elongated, wormlike body. Some worms have actual heads with eyes and sensory tentacles, but many don’t. The great many polychaete worms that live in tubes don’t have much of a head at all: usually all you can see sticking out of the tube is a crown of tentacles used for feeding. Although even the use of the word ‘crown’ more than suggests the presence of a head, doesn’t it? After all, where else does one wear a crown?
Most worms, including the worm that we imagined above, are bilaterally symmetrical, with bodies elongated along the Anterior-Posterior axis. This means the head is at the anterior end and the rear is the posterior end. For animals that don’t have a prominent head, the Anterior can also be defined by the direction of locomotion. Worms crawl with their bellies against the ground, which sets up a second axis of symmetry, the Dorsal-Ventral axis. The third axis of symmetry is the Left-Right axis. These axes should sound familiar, because they apply to our own bodies, as well of those of all other vertebrates and many invertebrates. Because of our upright stance we actually walk with our ventral surface forward, which is a little confusing, but if you don’t trust me you can see for yourself by crawling around on hands and knees for a while.
Now back to our worms, hypothetical and otherwise. Consider a worm that is elongated not along its Anterior-Posterior axis, but along its Dorsal-Ventral axis. It sounds strange, but such worms do exist. They are called phoronid worms, and are classified within their own phylum, the Phoronida. They all live in tubes, and the few times I’ve seen them they have been in pretty dense aggregations. As with most tube-dwelling worms the only part of the body that you can usually see is the crown of feeding tentacles, which in these animals (as well as in the Bryozoa and Brachiopoda) is called a lophophore.
The other day I was at the harbor looking for slugs with my friend Brenna, and spotted these pale tentacles swaying in the current.
These are the lophophores of an aggregation of phoronids! I’d never seen them at the harbor before, so I was pretty excited about it. They were on the side of a floating walkway, down almost beyond the reach of my outstretched arm. The current caused the lophophores to sway continuously and I was barely able to snap some blurry photos without falling in (I couldn’t really see what I was doing and just hoped for the best) when I accidentally caught this one shot. I wanted to have at least one clear-ish shot to submit to iNaturalist. I did manage to scrape off some bits of stuff that I hoped contained intact phoronids, so I could observe them under the dissecting scope at the lab.
And these are some lovely little worms!
The tubes that these phoronids inhabit are more like burrows of slime to which the surrounding sediments adhere. The tube itself isn’t anything particularly interesting, but the bodies of the worms are beautifully transparent. One of the coolest things you can see in a living phoronid is its circulatory system. They have red blood that, like ours, contains hemoglobin, so it’s easy to see the vessels that run along the length of the worm (which is the Dorsal-Ventral axis, remember) and the two blood rings around the base of the lophophore. If you get the lighting right you can even see the vessels that extend into each tentacle of the lophophore.
Single phoronid worm extending its lophophore 18 September 2017
I was disappointed to see that none of the video clips I took really do justice to these worms. They are so pretty when I look at them through the microscope, and I wish I could capture their beauty. You may at least be able to see blood moving through the larger vessels of the body in this short video.
Seems I need to upgrade my photomicroscopy set-up. Anybody have a few thousand bucks they want to donate to the cause?
I’m keeping the phoronids for as long as I can, although I don’t know what to feed them. I had time to take just a quick look at them this morning, and they look fine. Just for kicks I offered them a little phytoplankton to see what they’d do with it and couldn’t see if they were reacting at all. Still, they are filter feeders, and if I can adjust the lighting and get a good view of those ciliated tentacles I should be able to see if they are creating a water current that is bringing food to the mouth. Friday is the next day I have time to spend with these animals that I don’t get to see very often. Maybe then I’ll have something else to report.
For several centuries now, Earth’s only natural satellite has been associated with odd or unusual behavior. Lunatics were people we would describe today as mentally ill, who behaved in ways that couldn’t be predicted and might be dangerous. The erratic behaviors were attributed to the vague condition of lunacy. These words are derived from the Latin luna, which means ‘moon’. The cycles of the moon have long been thought to influence human behavior as well; hence such legends as the werewolf.
We do know that the moon indeed has a very strong influence on aspects of many organisms, primarily through the tides. For example, reproduction in many marine animals is timed to coincide with a particular point in the tidal cycle. Grunion (Leuresthes tenuis, small, silver, finger-shaped fishes) run themselves up onto California beaches at night to spawn following the full and new moon high tides in the early summer months. Corals in the Great Barrier Reef spawn together in the handful of nights after the full moon in November. Animals such as these, which reproduce via broadcast spawning, are the ones most likely to benefit from synchronized spawning; after all, there is no point in spawning if you’re the only one doing it. Invertebrates don’t have watches or calendars; they keep time by sensing the natural cycles of sun and moon. The moon’s strong effect on the tides is a signal that all marine creatures can sense and use to coordinate spawning, increasing the probability of successful fertilization for all.
Last night, Wednesday 6 September 2017, the moon was full. Yesterday at the lab, I noticed that the large Anthopleura sola anemones living in the corner of my table had spawned.
That diffuse grayish stuff in the right-hand side of the photo is a pile of sperm. I looked at a sample under the microscope, just to be sure. By this time they had been sitting at the bottom of the table for several hours and most of them were dead. But they were definitely sperm:
Whenever I see something unusual like this my first impulse is to see if it’s happening anywhere else at the lab. So I started poking around. The aquarists at the Seymour Center told me that some of their big anemones had spawned in the past couple of days; however, since they clean and vacuum the tanks every day all evidence was long gone.
Fortunately there are several A. sola anemones in other labs that aren’t cleaned as regularly as the public viewing areas. One of the animals in the lab next door to where I have my table had also spawned. . .
And the eggs are really cool. See those spines? They are called cytospines and apparently deter predation. Other species in the genus Anthopleura (A. elegantissima and A. xanthogrammica) are known to have spiny eggs, so it appears that this is a shared feature. Now, if only I could get my hands on eggs of the fourth congeneric species–A. artemisia, the moonglow anemone–that occurs in our area, I’d know for certain, at least for California species. I examined the eggs under higher magnification, but due to their opacity I couldn’t tell if the had been fertilized. Most appeared to be solid single undivided cells; they could, however, be multicellular embryos.
All told, of the anemones that had obviously spawned, 1 was female and 4 were male. I sucked up some of the eggs and put them in a beaker of filtered seawater. I doubt that anything will happen, but I may be in for a pleasant surprise when I check on them tomorrow.
This is the time of year when whales visit Monterey Bay and often come quite close to shore. Humpbacks, in particular, are commonly seen from beaches in the fall. Earlier in the summer they are out over the Monterey Canyon feeding on krill. In the late summer and early fall they switch to feeding on anchovies, which school in shallower water over the continental shelf. Last week they were putting on a show, to the delight of whale watchers who pay for whale watching trips out of Moss Landing and Santa Cruz.
Yesterday evening my husband and I borrowed a friend’s little boat and went out looking for whales. A humpback had been seen from the beach around the cement ship at Seacliff State Beach, lunge-feeding and breaching. Even the Monterey Bay is a big body of water, and I’d rated our chance of finding a whale at about 50%. We did eventually find one swimming parallel to the shore. And I have pictures to prove it!
The Marine Mammal Protection Act of 1972 prohibits humans from approaching any marine mammals, so we kept our distance. The whale undoubtedly knew we were there and it did get a little closer than this, right around the time that we noticed a flock of ~25 pelicans fly overhead and start circling over an area a short distance away. It was starting to get dark and we had to turn around and head back, and on our way we ended up where the pelicans were hanging out.
As we approached we could see a bird flapping about on the surface of the water, but unable to get airborne. It didn’t take long for us to see that it was somehow tied up with a dead common murre and a piece of kelp. We were able to pull the kelp toward the boat and grab the live bird. It appeared to be a juvenile gull.
It had a hook in its right nostril and a hook in each foot. The hook in its beak was attached to line that went around its body, making the bird unable to raise its head. Fortunately Alex was able to cut the line while I held the bird. We didn’t have the tools to try removing the hooks, so we decided to head back in. We wrapped the bird loosely in a towel to keep it from flailing around and held onto it for the long, wet ride back to the harbor.
When we back on land I called the Marine Mammal Center because: (a) I had the number programmed into my phone; and (b) I knew they’d have a live person to answer the phone, who would be able to tell me who to call about this bird. The person I talked to transferred me to Pacific Wildlife Care in Morro Bay. The recorded message told me to place the bird in a box or pet carrier on a towel and leave it in a warm, dark place until we could bring it in the morning. We weren’t about to make a 2.5-hr drive to Morro Bay, but fortunately there is an organization right here in Santa Cruz that we’ve taken animals to before: Native Animal Rescue. We got home, dug out the kitty carrier, and tucked the bird in for the night. The only warm place we could think of that the cats couldn’t get to was the pantry, so the bird spent the night there.
I had a school meeting this morning, so Alex took the bird to Native Animal Rescue. The woman who met him said the bird was a juvenile western gull (Larus occidentalis)–another WEGU. She took the bird out, wrapped it in a towel, and calmed it by simulating a hood on its head.
The woman pulled the hook out of the nostril pretty easily. To remove the hooks from the feet she had to first cut the barbs and then pull them back out. Alex said the whole thing took about 5 minutes. The bird seems otherwise uninjured. The folks at Native Animal Rescue will keep an eye on it for a few days and then release it back to the wild. I think I’ll give them a call tomorrow and see if we can be there when the bird is released.
Update Sunday 20 August: We called Native Animal Rescue this morning and were told that the bird had been transferred to a wildlife care facility up in Fairfield. All of the seabirds that come into Native Animal Rescue get sent up there. So we won’t get to see “our” gull be released back into the wild.
The intertidal portion of my participation in Snapshot Cal Coast 2017 is complete. I organized four Bioblitzes, two of which consisted of myself and Brenna and the other two for docents of the Seymour Marine Discovery Center (Tuesday) and the docents of Año Nuevo and Pigeon Point State Parks (Wednesday). The four consecutive days of early morning low tides have been exhausting for a concussed brain and a body dealing with bronchitis for the past several weeks. Good thing the low tide arrives 40-50 minutes later, or I’d probably be dead by now. And even so, I tried to take advantage of the later tides to venture a bit farther afield, so I still ended up getting up at the butt-crack of dawn.
But oh, so totally worth it!
Day 3: Davenport Landing with docents from the Seymour Marine Discovery Center, Tuesday 27 June 2017, low tide -1.1 ft at 08:03
Davenport Landing Beach is a sandy beach with rock outcrops and a fair amount of vertical terrain to the north, and a series of flat benches (similar to those at Natural Bridges) to the south. To get to the good spots at the north end you have to do some cliff scrambling, unless the tide is low enough that you can walk around the rock, which happens maybe once or twice a year. Because it’s easier to get around on the benches to the south, that’s where I took my group for the Bioblitz. The difference in topography also results in some differences in biota and distribution/abundance of organisms; overall biodiversity is probably equivalent at both sites, but certain species are more abundant at one site versus the other.
The morning we went to Davenport was sunny and (almost) warm. This makes for plenty of light for photography, but also lots of glare of the surface of pools and the wet surfaces of organisms themselves. My most successful photos are the ones I took with the camera underwater. Wanting to improve my skills at identifying algae, I concentrated most of my efforts on them while not ignoring my beloved invertebrates.
Coralline algae are red algae whose cells are impregnated with CaCO3. This gives them a crunch texture that is unusual for algae. Corallines come in two forms, encrusting and upright, and can be one of the most abundant organisms in the high and mid intertidal. There are several species of both encrusting and upright corallines on our coast, and most of the time they aren’t identifiable to species by the naked eye. Sometimes I can distinguish between genera for the upright branching species. However, the encrusting species require microscopic examination of cell size, crust thickness, and reproductive structures, none of which can be observed in the field.
Some algae are so distinctive that a quick glance is all it takes to know exactly who they are. With its tiny holdfast, long elastic stipe, and single large pneumatocyst, bullwhip kelp doesn’t look anything like the other kelps in California. Like most kelps, N. luetkeana lives mostly in the very low intertidal or subtidal, where under certain conditions it can be a canopy-forming kelp. About a month ago I noted a big recruitment of baby Nereocystis kelps in the intertidal on the north side of Davenport Landing Beach. I speculated then that they probably wouldn’t persist into the summer. I’ll have to take a morning soon to go up and check on them. Anyway, on our Tuesday Bioblitz we found this big N. luetkeana growing in the intertidal. The stipe was about 1.5 meters long and the pneumatocyst was a little smaller than my closed fist. Given that this individual recruited to that spot and has persisted for a few months, probably, it has a good chance of continuing to survive into the fall. Winter storms, especially if they’re anything like the ones we had this past year, will most likely tear it off, though.
Coralline algae aren’t the only pink things in tidepools. There are pink fish!
Sculpins are notoriously difficult to ID if you don’t have the animal in hand to count things like fin rays and spines. Someone on iNaturalist may be able to ID this fish, but I don’t think the photo is very helpful.
And, just because they’re my favorite photographic subjects in the intertidal, here’s a shot of Anthopleura sola:
As of this writing, 10 participants in this Bioblitz have submitted 204 observations to iNaturalist, with 70 species identified. I know that some people haven’t upload their observations yet, and expect more to come in the next couple of weeks. The docents enjoyed themselves, to the extent that two of them accompanied Brenna and me to our fourth Bioblitz at Pigeon Point.
Day 4: Whaler’s Cove at Pigeon Point with rangers (and one docent) from Pigeon Point and Año Nuevo state parks, Wednesday 28 June 2017, low tide -0.6 ft at 08:53
Usually when I go to Pigeon Point I go to the north side of the point, either scrambling down the cliff next to the lighthouse or about half a mile north to Pistachio Beach. When the park rangers and I were organizing this Bioblitz they suggested going to Whaler’s Cove, as the access is very easy due to a staircase and would be much easier for docents who aren’t used to climbing down cliffs. It ended up being a good decision, as there was much to be seen.
Bioblitzes and iNaturalist are all about photographing individual organisms (as much as possible) so that they can be ID’d by experts in particular fields. This is the ‘tree’ level of observation I mentioned in my previous post. I find that when I’m taking photos with the intent to upload them to iNaturalist the photos themselves tend to be rather boring. The intertidal is such a dynamic and complex habitat that photos of single species tend to lack the visual interest of the real thing. I’ve learned that one of my favorite things to see is organisms living on other organisms.
Four of this chiton’s eight shell plates are completely covered with encrusting coralline algae. It is also wearing some upright corallines and at least two other red algae, one of which is Mastocarpus papillatus. This photo produced six observations for iNaturalist.
Which is not to say that single-subject photos are always boring. When the subject is as weighty as this gumboot chiton (Cryptochiton stelleri), it deserves its own photo or two.
The largest chiton in the world, Cryptochiton typically lives in the subtidal or the very low intertidal. Unlike other chitons, it doesn’t stick very firmly to the substrate. I was able to reach down and pick up this one with very little effort. In the subtidal this lack of suction isn’t a handicap, as water movement there is less energetic compared to the intertidal, and Cryptochiton does quite well. But it doesn’t really look like a chiton at all, does it? That’s because its eight dorsal shell plates are covered by a thick, tough layer of skin called the mantle. In most chiton species the mantle is restricted to the lateral edges of the dorsal surface. The girdle, as it’s called, exposes the shell plates to some degree. We don’t see Cryptochiton‘s shell plates, but if you run your finger down the middle of the dorsum you can sort of feel them underneath the mantle.
I love this one. There’s a lot going on in this small area. The greenish-brown algae are actually a red alga, Mazzaella flaccida. There are two large clumps of stuff in the photo. The clump on the left, consisting of round lumps, is a clone of the aggregating anemone Anthopleura elegantissima. The other clump is a mass of tubes of the polychaete worm Phragmatopoma californica. These two clumps were formed in very different ways, reflecting the vastly different biology of the animals that made them.
Anthopleura elegantissima is one of four species of Anthopleura anemones we have in California and is the only one to grow by cloning. It does so via longitudinal fission, in which an anemone literally rips itself in half. I wrote about them last year. Note that in this aggregation, all of the anemones are about the same size. That’s because they’re all clones of each other and share the exact same genetic makeup.
Whereas a clone of A. elegantissima represents a single genotype formed by cloning, clumps of Phragmatopoma arise by gregarious settlement. Each of the tubes in a clump is occupied by a single worm, which recruited to that spot as a larva and settled down to live its life. When it comes time to look for a permanent home, the planktonic larvae of Phragmatopoma are attracted by the scent of adult conspecifics. The larvae settle on the tubes of existing adults and undergo metamorphosis. Each worm builds its tube as it grows, using some kind of miraculous cement that sticks sand grains together, much as a mason stacks bricks to build a wall. One of the remarkable things about this construction is that the cement is secreted by the animal’s body and starts out sticky and then hardens, all in seawater. It’s a likely candidate for Best Underwater Epoxy around. Interestingly, Phragmatopoma can build its tube only as a growing juvenile. Adult worms that are removed from their tubes do not build new ones, and soon die.
See that pile of rocks out there? That’s where we were blitzing. Given the not-so-lowness of the tide I didn’t know if we would be able to make it out there. We were lucky, though, and were able to spend ~30 minutes out on that little point.
So far, the Pigeon Point Bioblitz has yielded 204 observations for iNaturalist, with three participants (so far!) identifying 77 species. Several of my observations were of red algae that I did not recognize; hopefully an expert will come along to ID those for me. Snapshot Cal Coast 2017 continues through this weekend. My intertidal Bioblitzes are over, but I hope to contribute one last set of observations by collecting and examining plankton on Sunday.
This is the second year that the California Academy of Sciences has sponsored Snapshot Cal Coast, a major effort to document and characterize the biodiversity of the California coast. To this end the Academy has organized several Bioblitzes at various sites in northern California, and solicited volunteers to lead their own Blitzes, either as individuals or with groups. A Bioblitz is a citizen science activity in which people take photographs of organisms or traces of organisms (shells, scat, tracks, etc.), then upload their observations into iNaturalist. Experts then identify the organisms in the observations, and the data are publicly available to anyone who wants to use them.
For Snapshot Cal Coast 2017 I have four Bioblitzes planned for the intertidal. Here are some of my observations made in the first two.
Day 1: Natural Bridges, Sunday 25 June 2017, low tide -1.7 ft at 06:27
My friend Brenna joined me on an early low tide at Natural Bridges. The intertidal topography at Natural Bridges consists of a series of gently sloping benches that are riddled with potholes of various sizes and depths. For the purposes of this Bioblitz I decided to confine my observations to the geological structure that I call the peninsula, which sticks out farther into the ocean than the edges of the benches.
The peninsula is most easily accessible when the tide is at least as low as -1 ft, although large swell can make it entirely unsafe to do so at even very low tides. Fortunately the swell wasn’t big enough to keep me from the peninsula yesterday, and I confined most of my observations to this location. I’ve found that making observations for Bioblitzes requires a different kind of attention and focus than either collecting or observing for more general purposes. In the spectrum of forest-to-trees levels of observation, Bioblitzes are all about individual trees. When left to my own devices I tend to move quite fluidly between forest-level observations (e.g., broadscale ecological patterns) and tree-level observations (e.g., what organism is that?), and confining myself to only tree-level observations was, well, confining. It’s undoubtedly a good discipline, but one that I find a little stifling.
Here are some of the “trees” I saw at Natural Bridges.
I’ve been keeping an eye on this abalone for a couple of years now. It has gotten bigger and in the last year has become heavily encrusted with other animals and algae. Right now it is sporting lots of acorn barnacles (both large and small), at least one tube of Phragmatopoma californica, limpets, encrusting and upright coralline algae, and other red algae.
Smithora naiadum is a red alga whose thallus consists of small flat blades. It grows only as an epiphyte on seagrasses, in this case the surfgrass Phyllospadix scouleri. Later in the summer many surfgrass leaves will be almost entirely covered with Smithora.
My favorite observation of the morning was this little hermit crab.
I love how this hermit is clinging to a piece of giant kelp. It lives in a shell of the olive snail Olivella biplicata, as many of its conspecifics do. These shells get to a bit over 2 cm in length, and their narrow diameter means there isn’t much empty space inside. Fortunately, P. hirsutiusculus is one of the smaller hermit crabs and doesn’t need much space.
An extreme low tide like yesterday’s has two benefits. The most obvious is that more real estate is exposed, thus more area to explore. The second benefit of a really low tide is time. Much of the biodiversity of the intertidal is in the low-mid and low zones; the lower the tide, the longer it takes for the ocean to return and reclaim its property. I was able to spend the better part of two hours out on the peninsula, which doesn’t happen every year. Lucky me!
Day 2: Franklin Point, Monday 26 June 2017, low tide -1.5 ft at 07:15
To get to the beach at Franklin Point you have to hike ~10 minutes over the dunes along a maintained trail. The views along the way are often quite spectacular, even when it’s foggy. This morning it was unusually clear, and I wished I had brought along my big camera. For example, looking north towards Pigeon Point I saw this:
I mean, come on. How much more beautiful can a vista be?
The intertidal at Franklin Point has changed dramatically over the past year. Heavy storms over the 2016-2017 winter removed about two vertical meters of sand from the beach, exposing rocks that had been buried for years. Even today, months after the peak of the storm season, you can see bare rock that has yet to be heavily colonized by living things.
Primary succession is the sequence of species’ arrival and eventual replacement in an area that has never hosted life before. These rocks may very well have served as habitat for organisms years ago, but in my memory they had been buried in sand until the recent storms. Their exposure provides an opportunity to observe primary succession in this very dynamic habitat.
The first organisms to arrive and take hold in any newly available habitat are primary producers. Makes sense, as there is no food for heterotrophs yet. In the case of the intertidal the first visible organisms are algae. The algae at Franklin Point have been going like gangbusters all spring and into the summer. Faunal diversity, on the other hand, has been rather low. I spent quite a while looking at and photographing algae, many of which I couldn’t identify in the field.
Some things were entirely unfamiliar to me. For example, I’d never seen coralline algae encrusting on the tips of another red alga. And yet, here it is:
As I mentioned above, animal life at Franklin Point has been rather depauperate this year. HOWEVER, I did get to let out a few whoops of triumph when I found this:
These animals, staurozoans, are incredibly difficult to photograph. Not only are they the same color as many of the algae they live with and attach to, but they like areas where the water is constantly moving back and forth. Plus, the pools and channels where I found them were cloudy with Ulva spooge. I took a lot of pictures of backscatter and blurry staurozoans.
Staurozoans are the strangest and by far the coolest cnidarians. Their common name ‘stalked jellyfish’ harkens back to when they were considered scyphozoans, close kin to moon jellies (Aurelia) and the like. They are now known to be in their own group, the Staurozoa, related to but not part of the Scyphozoa.
I don’t really know why I’m so enamored of the staurozoans. Maybe it’s because they are rare and poorly understood. I know them only from Franklin Point and one sighting at Carmel Point. The systematics of the staurozoans is in flux; I’m not brave enough to assign a species epithet to this critter, but a colleague who is one of the people working on this group suggests that it is H. sanjuanensis, a species that has not yet been formally described. All of the staurozoans I saw today were this brownish-red color, but in previous years I’ve also seen them in a brilliant bottle green. Those would probably be easier to see among all the red algae, but with my luck the green ones would all be hanging out with Ulva.
The very last part of the hike to the intertidal is a steep decline down the dune to the beach. Getting down is easy, you just sort of ski down. Getting up is much more of a challenge. Ever try to climb a sand dune? Each step gets you about a quarter of a step above the last one, so it’s hard work, especially when the dune is steep. There have been times that I’ve hiked all the way out to the beach, only to turn around and go back because I didn’t think I’d be able to climb back up the dune in my hip boots. And since I have bronchitis right now by the time I got back to the top today it felt as though I had climbed Mt. Everest.
All told, I added about 150 observations to iNaturalist these first two Bioblitzes. I’m not really into making observations just to make observations, so for me that 150 is a good two days’ production. Now I need to rest up for tomorrow’s low tide.
If anyone remembers, 2015 was a year of strange weather. The Blob of warm water in the northeast Pacific governed weather patterns throughout California, and we had an unusually warm and sunny summer, with none of the normal fog on the coast. Nature’s air conditioner went on the fritz that year.
Since I spent most of 2016 in the mental fog of concussion I’m not sure I can recall with any accuracy whether or not last year was a normal year. So far 2017 feels like a return to old times, at least in terms of the intertidal biota. I’ve seen fewer of the species that creep up the coast during El Niño, such as the pink blobs of bubble gum called Hopkins’ rose, which were spattered everywhere in 2015. The algae are lusher than I’ve seen in what feels like forever, but was probably only about three years.
Both species of surfgrass seem to be doing well, too. The two species, Phyllospadix torreyi and P. scouleri often grow side by side in the exact same spot. Just the other day I saw the season’s first flowers on P. scouleri at Pigeon Point.
The two species of Phyllospadix can be distinguished by the shape of their leaves. Phyllospadix torreyi‘s leaves are narrow and sometimes cylindrical in cross-section, while P. scouleri has flatter, more ribbon-like leaves. Phyllospadix scouleri can also be a darker bluish-green color, compared to P. torreyi‘s brighter spring green color.
At Pistachio Beach I saw that P. scouleri has started to bloom. In one patch I found some fresh flowers, and in the stiller pools the water was covered with a yellow film that I think is the pollen.
When the growing is good, the algae recruit to any available surface. This includes the thalli of established algae, or the bodies of animals. Any surface will do, and the hard shells of molluscs are often fouled by algae and/or small animals.
The mossy chiton, Mopalia muscosa, seems to be especially susceptible to fouling by algae. Or, it could be that it tolerates or even benefits from the population of algae growing on its shell plates. Whatever the reason, M. muscosa often carries more algae around than the other chitons.
Even the owl limpets aren’t immune to serving as substrate for other organisms. Here’s a large limpet sporting a collection of acorn barnacles, smaller limpets, and a jaunty off-center cap of red algae.
I’ve been seeing lots of echinoderms in the intertidal, too. The globular ones and the star-shaped ones, at least. Sea urchins (Strongylocentrotus purpuratus) seem to be more common than they have been in recent years, and we are having a bumper crop of the six-armed stars in the genus Leptasterias. Just the other day I saw a Leptasterias star that was brooding her babies:
Brittle stars are notoriously difficult to photograph, as they are extremely active and do not like the light. As soon as you get one situated for the camera, it starts crawling around to the back side of whatever you place it on. They aren’t happy unless they are safely hidden in the dark. This one, recorded in July 2015, was cooperative only because I didn’t really disturb it; I got lucky and happened upon it in deep enough water that I could dunk the camera without having to move the animal.
Good times out there! I hope this apparent return to cold-water flora and fauna sticks. It’s totally worth freezing on a damp, drizzly morning, to see the intertidal looking so vibrant and healthy. Cold water is good, productive water!
It seems that most years, the Memorial Day weekend brings some of the lowest spring tides of the year, and 2017 certainly fits the bill. I’ve been out for the past two days, heading out just as the sun is starting to rise, and already I’ve seen enough to whet my appetite for more. And with plans for the next few days, I’m pleased to say that my dance card is completely full for this tide series. There are a lot of stories building out there!
At this time of year everything is growing and reproducing. Many of the larvae I’ve seen in the plankton have parents that live in the intertidal; makes sense that those parents should be having sex now. Barnacles, for example, copulate when the tide is high. I’ve seen them go at it in the lab, but never in the field, as they don’t mate while emersed. This morning I interrupted a pair of isopods locked in a mating embrace, and they swam off, still coupled together, when I disturbed them. Other animals were much less shy. Lifting up a curtain of Mazzaella to see what was underneath, I spotted a small group of dogwhelks (small, predatory snails). I can’t be certain, but suspect they were having an orgy.
A short distance away I found the inevitable result of the dogwhelk orgies.
Each of those urn-shaped objects is an egg capsule, containing a few dozen developing embryos. After the snails copulate the mating individuals go their separate ways. The females lay these egg capsules in patches in the mid-intertidal, usually on a vertical surface under the cover of algae to minimize the risk of desiccation.
For many years now, some of my favorite animals have been hydroids. I worked in a hydroid lab as an undergraduate, and this is when I fell in love with the magic of a good dissecting microscope. A whole new world became visible, and I found it easier than I ever imagined to fall under the spell of critters so small they can’t be seen with the naked eye. I still do.
Hydroid colonies come in a variety of forms, shapes, and colors. Most of them are small and cryptic, resembling plants more than any ‘typical’ animal, and aren’t easily seen unless you’re looking for them. One intertidal species, however, is pretty conspicuous even to the casual tidepool visitor or beachcomber. It often gets torn off its mooring and washes up on the beach.
A hydroid colony is the benthic polyp stage of the standard cnidarian life cycle. The polyp represents the clonal phase of the life cycle and reproduces by dividing to make several copies of itself. In a colony such as a hydroid, the polyps remain connected to each other and even share a common digestive system. The polyps don’t reproduce sexually. That function is reserved for the medusa stage of the life cycle. Some hydroid colonies produce free-swimming medusae, and others hang onto reduced medusa buds or structures so un-medusa-like that they’re called gonangia. Aglaophenia is a hydroid that houses its sexual structures in gonangia that are located on the side-branches of the fronds.
Here’s a closer view of a single frond of the Aglaophenia colony. I had to bring it back to the lab to look at it under the scope.
The gonangia look like leaves, or pages of a book, don’t they? After working a low tide I’m always hungry, and when the lows are early in the morning I’m often cold and sleep-deprived as well. That’s my excuse for not dissecting open one of the gonangia to see what’s inside.
Even the algae are getting into the act of reproducing and recruiting. This spring I’ve noticed a lot of baby bullwhip kelps (Nereocystis luetkeana). Nereocystis is one of the canopy-forming kelps in subtidal kelp forests along our coast, but every year some recruit to the low intertidal. However I don’t remember seeing so many baby Nereocystis thalli in the tidepools. The smallest one I saw this morning had a pneumatocyst (float) the size of a pea! In mature thalli, the float might get as big as a cantaloupe.
Nereocystis doesn’t usually persist or get very large in the intertidal. It is more common to see detached thalli washed up on the beach than to see a living bullwhip kelp longer than about 2 meters in the intertidal. Whether or not this particular nursery area results in an established population remains to be seen. I’m betting ‘No’ but could very well be proved wrong. Only time will tell.
If I ask my invertebrate zoology students to name three characteristics of the Phylum Annelida, they would dutifully include segmentation and chaetae (bristles) in the list. And they would be correct. Annelids, for the most part, are segmented and many of them have chaetae. But in biology there are many exceptions for every rule we teach, and it’s these exceptions that make a deeper study of biology so rewarding.
A couple of weeks ago I did some collecting in the intertidal at Pigeon Point. It was a very accommodating low tide, and I had a lot of time to poke around and explore. I found an area that had several decently sized rocks that I could turn over, and had fun seeing what lives on the side away from the light. Some of the animals on the underside of rocks are the common ones you see everywhere–turban snails, limpets, Leptasterias stars, and the like. Some, however, prefer a life of darkness and actively move away from the sun when their rock is turned over. And others happen to live in the sand under the rock and might not care one way or the other about the light.
Peanut worms, scientifically known as sipunculans, are delightful small worms that in my opinion are vastly underappreciated. This is understandable, as they are usually hidden in sand or rubble and aren’t exactly conspicuous even when uncovered. Phascolosoma agassizii is our local sipunculan. Like all sipunculans it is unsegmented, and it has no chaetae. Peanut worms used to be elevated to their own phylum, the Phylum Sipuncula; however, molecular evidence shows that they are indeed annelids despite their apparent loss of key features such as body segmentation and chaetae.
They do look vaguely peanut-ish, don’t they? They’re small, maybe 6 cm all stretched out, which you hardly ever see. Phascolosoma agassizii is a grayish pink color, with irregular black stripes that usually don’t form complete hoops around the body. Peanut worms are sedentary, living with most of the body buried in sand, rubble, shell debris, kelp holdfasts, etc. One of the weird things about them is that the mouth in located on the distal end of a long tube called the introvert. Most of the time the introvert is stuffed inside the main body region, or trunk. It is eversible and unrolls from the inside out, sort of like when you remove a long sock by pulling the top edge down over your leg and off your foot. The mouth on the end of the introvert is surrounded by short sticky tentacles, and the introvert dabs around to pick up organic deposits from the surfaces. Mucus and cilia on the tentacles convey the yummy organic gunk to the mouth, and a pharynx pushes food through to a long esophagus that runs the length of the introvert and leads to the long coiled intestine in the trunk.
Watch these peanut worms extending and retracting their introverts. Cute, aren’t they?
I brought three peanut worms back to the lab with me, where they are happily living in my sand tank. Their housemates are ~15 sand crabs (Emerita analoga) and a clump of tube-dwelling polychaetes (Phragmatopoma californica). I never see them unless I dig them up from the sand, which leads me to believe that they do most of their feeding at night. Either that or they actually do actively shy away from the light.
Despite not sharing much in the way of apparent morphological similarity with more typical annelids, sipunculans are indeed annelid-like in other ways. Many of their internal structures are like those of annelids, and at least their early development (cleavage pattern and differentiation of tissue layers) follows the annelidan pathway. The species that have indirect development have a trochophore larva, typical of the marine annelids, that in some cases morphs into a second larval stage called a pelagosphera.
Sipunculans are the poster child for Animals That Are Not What They Seem. But they are interesting in their own way, and I always have a “yay!” moment when I find them in the field. It’s really hard not to make sound effects as they’re rolling their introverts in and out. You should try it yourself some time.
One of the defining characteristics of the Phylum Mollusca is the possession of a shell, which serves both as a protective covering and an exoskeleton. We’ve all seen snails, and some people may have noticed that snails often withdraw entirely into their shells and even have a little door that they can use to seal up the opening of the shell. That little door is called the operculum. Opercula occur in non-molluscan animals, too, such as some of the tube-dwelling polychaete worms and some of the thecate hydroids. Snail opercula come in lots of different shapes, depending on the aperture of their owner’s shell.
Given the enormous morphological diversity within the Mollusca it shouldn’t be surprising that their shells vary immensely in prominence and shape. In fact, molluscan shells demonstrate quite beautifully the relationship between form and function. The benthic and most familiar molluscs, the gastropod snails, generally have coiled shells. Notable exceptions to this generality are the marine opisthobranchs (nudibranchs and sea hares) and the terrestrial slugs. And for the most part snail shells look recognizably like snail shells, even though some are plain coils, others may be flattened (e.g., abalones), and still others may be crazily ornamented. Aquatic animals crawl around in water, which helps to support the weight of heavily calcified shells. Terrestrial snails, on the other hand, live in a much less dense medium (air) and have lighter, less calcified shells. The trade-off for a more easily transportable shell is that air is also very drying, and a thinner shell provides less protection from desiccation.
I should state for the record right now that I’m not talking about the many molluscs that don’t have shells at all, or that have much reduced shells.
The bivalve molluscs (mussels, clams, oysters, etc.) live inside a pair of shells. They are sedentary animals, living either attached to a hard surface or buried in sand or mud. Not being able to run from predators (although some scallops can swim!), their only defense is the toughness of their shells and the strength of the adductor muscles that hold the shells closed. Most bivalves feed by sucking water into the shells through an incurrent siphon, using their gills to filter food particles from the water, and expelling the water through an excurrent siphon. To do so they must open their shells enough to extend their siphons, or at least expose inhalant and exhalant openings, to the water current surrounding them.
So, snails have one shell and bivalves have two. Some of the most interesting molluscs, in terms of shell morphology, are the chitons. The Polyplacophora (Gk: ‘many plate bearer’) have a shell that is divided into eight dorsal plates. This makes them immediately distinguishable from just about any other animal.
Chitons live from shallow water to the deep sea, but the majority of species live in the intertidal. This is a high-energy habit characterized by the bashing of waves as the tide rises and falls twice daily. Any organism living here must be able to hang on for dear life or risk being swept away to certain death. Chitons are certainly well equipped to survive in this habitat. They have a low profile, offering minimal resistance to the waves. Rather than stand tall and face the brunt of the wave energy, chitons cling tightly to the rocks and let the waves wash over them.
The chiton’s shell, divided into eight articulating plates, gives the animal a much more flexible shell than is found in any other mollusc. This allows them to conform to the topography of the rocks, giving them an even lower profile than, say, a limpet of the same overall shape and size.
While most chitons are pretty sedentary, at least during the low tides when we can see them, some of them can move pretty quickly when they want. So what, exactly, motivates a chiton to run? One species, Stenoplax heathiana, lives on the underside of rocks in the intertidal; it comes out at night to forage on algal films and retreats back under its rock with the dawn. I’ve seen them at Pistachio Beach, where I turned over rocks and watched them run away from the light. This video is shot in real-time; the chitons are really running fast!
When the eight shell plates are visible it’s easy to identify a chiton as a chiton. But not all chitons are quite so obliging with their most chiton-ish characteristic, and one is downright misleading.
Below is Katharina tunicata, one of the largest chitons on our coast. Its shell plates are barely visible, as they are almost entirely covered by the animal’s mantle, the layer of tissue that covers the visceral mass and encloses an open space called the mantle cavity in which the gills are located. In chitons, the mantle extends onto the dorsal side of the animal and is called the girdle. Katharina‘s girdle is smooth and feels like wet leather.
The largest chiton in the world is the gumboot chiton, Cryptochiton stelleri, and it lives on our coast. This beast is about the size of a football, reaching a length of 30 cm or so. It lives mostly in subtidal kelp forests, but can be found in the very low intertidal, which is where I usually see it. At first encounter it’s hard to figure out what this animal is. It certainly doesn’t look like a chiton.
If anything, it looks like a mostly deflated football, doesn’t it? Turning it over to look at the underside doesn’t help much, either, although this photo does give an idea of how big the animal can get:
Cryptochiton goes one beyond Katharina and covers its plates entirely. Just looking at the animal you’d have no idea that there are eight plates underneath the tough reddish-brown mantle, but you can feel them if you run your finger along the midline of the dorsum. Living subtidally as it does, Cryptochiton doesn’t have the ability to cling tightly to rocks that its intertidal relatives do, and it tends to get washed off its substrate and cast onto the beach during storms. I’ve never seen one on the beach that wasn’t very dead. Once a friend and I were trudging back up the beach after working a low tide, and encountered a dead softball-sized Cryptochiton. I mentioned that it would be nice to have a complete set of shell plates from one of these animals. My friend always carries a knife in her pocket, so we started an impromptu dissection right there on the beach. It didn’t take long to learn that the mantle of a gumboot chiton is really tough and difficult to cut through with a pocket knife. And even once we got through the mantle, dissecting the plates from the underlying tissue wasn’t going to happen with the tools we had with us. Besides, the stench was godawful even with our unusual tolerance for the smell of dead sea things. We abandoned that corpse.
Many beachcombers have found white butterfly-shaped objects in the sand, but not known what they are. They are definitely calcareous and feel like bone, but what kind of animal makes a bone shaped like this? Turns out this object is one of the shell plates from C. stelleri. They wash up frequently, never attached to their neighbors so they provide no clue as to what organism they came from.
In order to obtain a complete set of Cryptochiton plates, I’d have to start with an intact chiton corpse. I did happen upon another dead Cryptochiton on a beach somewhere I was allowed to collect organisms, and I brought it back to the marine lab. I remember spending a smelly afternoon cutting the plates out of the corpse and removing as much of the tissue as I could, then feeding the plates to various hungry anemones to take care of the rest. Some of the plates got a little broken during the extraction process, but I do have my very own full set!
Animal associations can be strange and fascinating things. We’re used to thinking about inter-specific relationships that are either demonstrably good or bad. Bees and flowering plants–good. Mosquitos on their vertebrate hosts–bad. In many cases the ‘goodness’ or ‘badness’ of these associations is pretty clear. However, there are cases of intimate relationships between animals of different species that cannot be easily categorized as good or bad.
Take, for example, the barnacles on the skin of gray and humpback whales. From the barnacles’ perspective the skin of a whale isn’t a bad place to live: as the whale swims through the water the barnacle is continually flushed by clean water, which should make feeding easier. But is the whale affected in any way by its barnacle passengers? I suppose they might increase the drag coefficient a little bit and make swimming marginally less efficient, and maybe they itch, although it’s hard to imagine that the whale would really care much one way or the other.
A week ago I went to the intertidal up at Pigeon Point. It’s a great spot for certain animals, especially the small six-rayed stars of the genus Leptasterias. These stars rarely get larger than 8 cm in diameter and always have six arms. I’ve been told by a friend who just happens to be a sea star taxonomist at the Smithsonian, that making species identifications in the field is very difficult for this genus, so I’ve stopped trying. I do know that some of the Leptasterias stars have slender rays and others have thicker rays.
The most common large star at Pigeon Point is the bat star, Patiria miniata. These stars get about as big as my outstretched hand, and come in a variety of colors. Last week I didn’t see very many Patiria, but all of them were reddish orange, like this one:
Unless they’re so abundant as to be annoying, I like picking up bat stars and looking at their underside. That’s because sometimes they have these little dark squiggles in their ambulacral groove:
That little squiggle is a polychaete worm, Oxydromus pugettensis. It is one of many polychaete worms that forms a symbiotic relationship with another animal species. Some symbiotic polychaetes live in the tubes of other worms, or within the shells of bivalves, for example. Oxydromus crawls around inside the ambulacral groove of Patiria, where it feeds on scraps of leftover food from the star’s meals. The worms don’t like light, and as soon as I picked up this star and flipped it over the worm started burrowing down between the star’s tube feet to get back to the dark. The next day I found another star with a worm and was able to take a picture of it before it disappeared.
Oxydromus pugettensis is clearly segmented, evidence of its annelidan roots. It doesn’t look very different from many other free-crawling polychaetes. A member of the family Hesionidae, it lives in fine silty sediments in the intertidal as well as in the ambulacral grooves of sea stars. According to one source, it is the most common intertidal member of its family along the California and Oregon coast. For reasons as yet undetermined, P. miniata seems to be the favored host, although I have also seen the worms in the ambulacral grooves of the leather star Dermasterias imbricata.
Over two days at Pigeon Point last week I examined a total of five bat stars, and all of them had worms. One of the stars had three worms! It’s possible that more worms were hiding deep within the ambulacral grooves, too. I always wonder how, in this type of association, the partners manage to find each other. How does one “lucky” star end up with three worms? Do the worms every migrate from one star to another? Does the star do anything to attract the worms? In what way(s) would the star benefit from having a few worms in its ambulacral regions? It does seem that the worms don’t stick around very long once a star is brought into the lab–I don’t know if they die or just leave on their own–but since they also live in the sand maybe they do actively migrate between stars. There hasn’t been much work done on these worms in recent decades, probably because of the overall decline in natural history studies. However, I’ll keep this worm in mind for my Marine Invertebrate Zoology students this fall, when one of them asks me for help coming up with an idea for his or her independent research project.
