Gastropods x3

Posted on by Allison J. Gong

This past Monday I did something rare for me: I returned to the same intertidal site I had visited the previous day. I enjoyed myself so much the first time that I wasn’t able to refuse an invitation to go out there again. The site, Pigeon Point, is one of my favorites, especially in all of its spring glory as it is now. It has always been a hotspot especially for macroalgal diversity, and so far this year appears to be living up to its reputation. The day before I collected several reds that I got to spend the next two days trying to identify.

Three intertidal gastropods at Pigeon Point. Top circular object: Thylacodes squamigerus; yellow elongated object in middle: Doriopsilla albopunctata; bottom purplish-black snail: Tegula funebralis.
1 May 2017
© Allison J. Gong

On Monday I was less overwhelmed by obsessed with algae and able to focus more on the animals, and was delighted to find a small cluster of Thylacodes squamigerus, the strange and fascinating vermetid snail. Nearby one of the vermetid snails was a yellow nudibranch (Doriopsilla albopunctata) and one of the common turban snails (Tegula funebralis). The chance proximity of three different gastropods brought to mind the incredible diversity of this group of molluscs.

The Gastropoda are the largest group within the phylum Mollusca, and can claim a fossil record that dates back to the early Cambrian, some 540 million years ago. They have been extremely successful throughout that long time and are the only molluscan group to have established lineages in both freshwater and on land (of the other molluscs, only the bivalves have made it into freshwater, with the remaining groups restricted to the sea). As you might expect, this evolutionary history has given rise to a mind-boggling array of body types and lifestyles. Let’s investigate this diversity by taking a closer look at the three gastropods in the photo above.

Gastropod #1 (Thylacodes squamigerus): Very few people, on seeing this animal for the first time, would guess that it’s a snail. Most would say that it’s a serpulid worm. The tube is calcareous, as it is for serpulid worms, and winds around over rocks in the intertidal.

Tube of the vermetid snail Thylacodes squamigerus at Pigeon Point
1 May 2017
© Allison J. Gong

A close look at the opening of the tube, however, reveals snail-like rather than worm-like features. Thylacodes even has a snail’s face, although I’ll admit it isn’t easy to see if you don’t know to look for it. And despite crawling under a ledge with my camera, I didn’t get the best view of a face. In this photo, however, you can at least see one of the cephalic tentacles:

View into the tube of Thylacodes squamigerus at Pigeon Point
1 May 2017
© Allison J. Gong

Living in a tube cemented onto a rock means that Thylacodes can’t go out and find food. It must instead catch food and bring it in. Thylacodes does so by spinning threads of sticky mucus that are splayed out into the water, where they capture plankton and suspended detritus. The threads are then reeled in and everything–mucus and food–is eaten by the snail. Thylacodes tends to occur in groups, and individuals within an aggregation contribute threads to a communal feeding net, which presumably can catch more food than the sum total of all the snails’ individual efforts.

Pretty unexpected for a snail, isn’t it?

Gastropod #2 (Tegula funebralis): The black turban snail is probably one of the most common and commonly overlooked animals in the intertidal. People don’t see them because these snails are, literally, everywhere from the high- down into the mid-intertidal. They are routinely stepped over as visitors rush to the lower intertidal, and ignored again as these same visitors leave the seashore. I love them. I keep them in the lab as portable lawnmowers for the seawater tables. They are incredibly efficient grazers, keeping the algal growth down. Plus, I think they’re cute!

If there’s such thing as a ‘typical’ marine snail, T. funebralis may very well be it. This little snail exemplifies several of the traits we use to define the Gastropoda: it lives in a coiled shell, it uses a radula for scraping algal film off rocks (yum!) and is torted. The shell is easy enough to understand, as everyone has seen a snail at some point, even if it was a terrestrial snail. The radula and torsion, however, may take a little explaining.

A congregation of Tegula funebralis at Mitchell’s Cove
8 June 2016
© Allison J. Gong

Many molluscs have a radula, a file-like ribbon of teeth that can be stuck out of the mouth and used for feeding. In gastropods the radula can be a scraping organ (as in Tegula and other herbivores such as limpets), a drill (as in the predatory moon snails, which drill holes into unsuspecting clams and then slurp out their soft gooey bodies), or a poison dart (as in the venomous cone snails). The radula of a grazer such as Tegula bears many transverse rows of sharp teeth, which are regularly replaced in a conveyor belt fashion as they are worn down. This assures that the teeth being used are always nice and sharp. Remember the radula marks made by the owl limpet (Lottia gigantea)?

An owl limpet (L. gigantea) in her farm at Natural Bridges
7 March 2017
© Allison J. Gong
Tegula funebralis clearing real estate in my seawater table
27 January 2017
© Allison J. Gong

Those zig-zaggy marks are made by the scraping of the radula as the limpet crawls over her farm. Tegula funebralis makes the same type of pattern in my seawater tables. All of that white territory is area that had been scraped clean of algae in about a day. Tegula is a very industrious little snail! And they’re not shy, either. I don’t have to wait a day or so for them to get acclimated when I bring the back to the lab. I can move them around from table to table and after a few seconds they poke their heads out and start cruising around. I’ve learned from watching them over the years that they seem to have an entrained response to the rising and falling of the tides, even after I bring them into the lab. For the first few weeks of captivity, every morning when I first get to the lab I find that several Tegula have climbed up the walls. I think they’re crawling up when the tide is high. I really should look at that more carefully. They never go too far, but sometimes they do drop onto the floor and I find them by stepping on them. Fortunately they are hardy creatures and the floor is always wet with seawater so as long as I find them within a day and plunk them back into the table they’re fine.

Now on to torsion. Torsion is difficult to explain, but let me try. The word ‘torsion’ refers to the twisting of the nerve cord and some internal organs that occurs during larval development of gastropods. Here’s how it works. Imagine a closed loop, like a long piece of string with the ends tied together. Lay the loop down on a table and it is just a simple loop. Pick up one end of the loop, twist it counterclockwise 180°, and lay it down again. Now you have a figure-8, right? That’s not exactly what happens in the living snail, but you get the picture.

Tegula and other snails have an elongated body that is coiled and crammed to fit inside the shell. If you could take Tegula’s body and stretch it out without breaking it (impossible to do, BTW), you’d see the figure-8 configuration of the nerve cord. Other internal organs are re-arranged by torsion, too. As a result, both the gill(s) and the anus now open into the mantle cavity which has been relocated over the head. This arrangement is ideal for keeping the gill(s) irrigated, but not so good for hygienic reasons. Fortunately, the mantle cavity itself is angled so that water flows through it in a more-or-less unidirectional manner, passing over the gill before the anus. Tegula and other marine snails undergo torsion while in the larval stage, and remain torted as adults. This is not the case in other gastropods, as we’ll see next.

Gastropod #3 (Doriopsilla albopunctata): Everybody loves the nudibranchs, because their brilliant colors make them easy to love. Unlike the oft-undetected Thylacodes squamigerus and the ignored Tegula funebralis, many of the nudibranchs are somewhat easy to spot in the field because of their flamboyance. This is a crappy picture, but you get the point.

Doriopsilla albopunctata at Point Piños
9 May 2015
© Allison J. Gong

Doriopsilla albopunctata is one of several species of yellow dorid nudibranchs lumped together under the common name ‘sea lemon’. Instead of the long fingerlike processes (cerata) that adorn the backs of the aeolid nudibranchs such as Hermissenda spp., the dorids have smooth or papillated backs that may be decorated with rings or spots. Dorids also have a set of branchial plumes on the posterior end of the dorsum; the number and color of these gills can often be used to distinguish similar species. Doriopsilla albopunctata has a smooth yellow back with little white spots, hence the species epithet (L: ‘albopunctata’ = ‘white pointed’), and white branchial plumes.

Doriopsilla albopunctata at Franklin Point
17 July 2015
© Allison J. Gong

Nudibranchs are gastropods, although in a different group from Thylacodes and Tegula. The marine slugs, of which the nudibranchs are the most commonly encountered, are in a group called the Opisthobranchia, whose name means ‘gill on back’ and refers equally to the cerata of aeolids and the branchial plume of dorids. In fact, these animals lack the typical molluscan gill that the snails have. They do have a radula, however, and crawl around on a single foot exactly like Tegula does.

An adult nudibranch’s body is elongated, unlike the coiled body of Tegula, and has no apparent signs of having undergone torsion. However, examination of larval nudibranchs shows that they do undergo torsion just like any other respectable gastropod. The weird thing is that some time during the transition from pelagic larva to benthic juvenile they de-tort, or untwist their innards so that their internal anatomy matches their external shape. Instead of having to poop on their own heads, nudibranchs have an anus that is sensibly located at the rear (no pun intended) of the body.

Torsion is one of those biological curiosities whose evolutionary origin is shrouded in mystery. How did such anatomical contortions evolve? Why do gastropods, and only gastropods, undergo torsion? And why do some gastropods tort as larvae, only to detort as they become adults? There are scientific hypotheses about the benefits of torsion, particularly to the larval stages, but nobody knows for sure. After all, none of use were there to watch when it happened.

This is just a tiny taste of the diversity of the Gastropoda. I think it’s cool to see three such different gastropods in a small spot of the intertidal. And no doubt there were more that I didn’t see. That’s one of the joys of working in the intertidal: that I so often see things I wasn’t even trying to find.

Different strokes

Posted on by Allison J. Gong

When it comes to the natural world, I have always found myself drawn to things that are unfamiliar and strange. I think that’s why I gravitated towards the marine invertebrates: they are the animals most unlike us in just about every way imaginable. Even so, some of them have bodies at least that are recognizable as being both: (1) alive; and (2) animal-ish. Think, for example, of a lobster and a snail. Each has a head and the familiar bilateral symmetry that we have. Obviously they are animals, right? I, of course, am most fascinated not by these easy-to-understand (not really, but you know what I mean) animals, but to the cnidarians and the echinoderms. And for different reasons. The cnidarians astound me because they combine morphological simplicity with life cycle complexities that boggle the mind. I hope to write about that some day. Today’s post is about my other favorite phylum, the Echinodermata.

For years now I’ve been spawning sea urchins, to study their larval development and demonstrate to students how this type of work is done. I have a pretty good idea of what to expect in urchin larvae and can claim a decent track record of raising them through metamorphosis successfully. Urchins are easy. To contrast, I have much less experience working with sea stars. I have found that some species are easy to work with, while others are much more problematic. Bat stars (Patiria miniata), for instance, are easy to spawn and raise through larval development into post-larval life. Ochre stars (Pisaster ochraceus), on the other hand, go through larval development beautifully, but then all die as juveniles because nobody has figured out what to feed them. I’ve already chronicled my and Scott’s attempts in 2015 to raise juvenile ochre stars in a series of posts starting here.

Sea urchins and sea stars have long been model organisms for the study of embryonic development in animals, for a few reasons. First, many species of both kinds of animals are broadcast spawners, which in nature would simply throw their gametes out into the water. This means that development occurs outside the mother’s body, so biologists can raise the larvae in the lab and observe what happens. Second, spawning can be induced by subjecting the parents to nonlethal chemical or environment stresses. Third, the larvae themselves are often quite happy to grow in jars and eat what we feed them. Fourth, the larvae of the planktotrophic species are often beautifully transparent, allowing the observer to see details of internal anatomy. Lucky me, I’ve been able to do this several times. And it never gets old.

All that said, there are differences between urchins and stars that force the biologist to treat them differently if we want them to spawn. For the species I work with, spawning occurs after I inject a certain magic juice into the animals’ central body cavity–urchins get a simple salt solution (KCl, or potassium chloride) and stars get a more complex molecule (1-MA, or 1-methyladenine). The fact that you can’t use the same magic juice for urchins and stars reflects a fundamental difference in gametogenesis and spawning in these groups of animals.

Female (left) and male (right) spawning purple sea urchins (Strongylocentrotus purpuratus)
20 January 2015
© Allison J. Gong

Sea urchins will spawn only if they have fully developed gametes. In other words, gametogenesis must be complete before gametes can be released to the outside. You can inject as much KCl into a sea urchin as you want, but if it’s the wrong time of year or the urchin doesn’t have mature gonads (due to poor food conditions, perhaps), it won’t spawn. I’ve never investigated the mechanism by which KCl induces spawning in ripe urchins, but here’s what I think happens.

When students dissect animals in my invertebrate zoology class, we use magnesium chloride (MgCl2) to narcotize the animals first. A 7.5% solution of this simple salt is remarkably effective at putting many animals gently to sleep, especially molluscs and echinoderms. Placing the animals in a bowl of MgCl2 and seawater causes them to relax and gradually become unresponsive. A longer bath in the MgCl2 puts them to sleep for good.

Given the relaxation effects of MgCl2 on urchins, I suspect that injecting a solution of KCl into the body cavity relaxes the sphincter muscles surrounding the gonopores. This relaxation opens the gonopore, and if the gonads are ripe the mature gametes are released to the outside. As I said above, I don’t know for certain if this is how it works, but the hypothesis makes sense to me. It also explains why that I can shoot up a dozen urchins and get none of them to spawn: the KCl might be doing what it normally does (i.e., opening the gonopores) but if the gonads aren’t ripe there are no gametes to be released.

For completely different reasons, injecting a star with KCl does absolutely nothing at all except probably make the animal a bit uncomfortable. The KCl may very well open gonopores as it does in urchins, but a star will never have mature gametes, especially eggs, to release in response to this muscle relaxant. This is because at least in female stars, meiosis (the process that produces haploid gametes) isn’t complete until the eggs have been spawned to the outside. What, then, is the magic juice used to induce spawning in stars, and what exactly does it do?

The magic juice is 1-methyladenine, a molecule related to the nucleobase adenine, most commonly known as one of the four bases that make up DNA. The nomenclature indicates that the difference between the two molecules is the addition of a methyl group (–CH3) to the #1 position on an adenine molecule:

Chemistry aside, what I’m interested in is the action of 1-MA on the eggs of sea stars. Meiosis, the process that produces gametes, has two divisions called Meiosis I and II. Meiosis I starts with a diploid cell (i.e., containing two sets of chromosomes) and produces two diploid daughter cells; these daughter cells may not be genetically identical to each other because of recombination events such as crossing over. It isn’t until Meiosis II, the so-called reduction division, that the ploidy number is halved, so each daughter cell is now haploid (i.e., containing a single set of chromosomes) and can take part in a fertilization event. In a nutshell, the end products of meiosis are haploid cells, all of which ultimately result from a single diploid parent cell.

In female sea urchins, the entire meiotic process is completed before the eggs are spawned, which is why the relaxation effects KCl can induce spawning.

In females of many other animal species, meiosis is arrested for some period of time after the Meiosis I division. For example, this happens in humans: baby girls are born with all of the eggs they will ever produce, maintained in a state of suspended animation after Meiosis I. It isn’t until puberty that eggs begin to complete meiosis, one egg becoming mature and being ovulated approximately monthly for the rest of the woman’s reproductive life. Sea stars are sort of like this, with the notable exception that a female star will ripen and produce thousands of eggs in any spawning event rather than doling them out one at a time.

One of the really cool things about working with sea star embryology is that I get to see the completion of meiosis after the eggs have been spawned. I know that the gonads have to reach a certain level of ripeness before 1-MA will induce spawning. Reviewing my notes from a course I took in comparative invertebrate embryology when I was in graduate school, I came across the mention of ‘polar bodies,’ tiny blobs that I remember seeing in just-fertilized sea star eggs but which I have never seen in sea urchin embryos. Then I needed to remind myself what polar bodies are all about.

Remember how there are two cell divisions in meiosis? Well, despite what’s shown in the diagram above, each of the divisions is asymmetrical. In other words, each division of meiosis produces one big cell and one tiny cell. The tiny cells are the polar bodies. They are too small to either divide or be fertilized, and generally die on their own. Here’s a chronology of what happens. First, a cell divides, producing a large cell and a tiny polar body:

I’ve x’d out the polar body in red because it cannot divide or be fertilized and will soon die. Then the large cell divides to produce the final egg and a second polar body:

It turns out that in sea stars things get even more complicated. 1-MA acts as a maturation-inducing substance in these animals, effectively jump-starting the eggs that have been sitting around in an arrested state after undergoing Meiosis I. This initiates the continued maturation of the eggs to the stage when they can be spawned. Even now, though, meiosis doesn’t complete until an egg has been fertilized, at which point the second polar body is produced. The production of that second polar body is the signal that Meiosis II has occurred, and the now-fertilized egg can begin its embryonic development.

Here’s a freshly fertilized egg of Pisaster ochraceus, with the two polar bodies smushed into the narrow perivitelline space between the surface of the zygote and the fertilization envelope:

Zygotes of the ochre star Pisaster ochraceus, showing two polar bodies
25 April 2017
© Allison J. Gong

Sea urchins, remember, do not have polar bodies when I spawn them. That’s because meiosis is complete by the time the eggs can be spawned, so the polar bodies have already died or been resorbed by the final mature egg. The photo of the P. ochraceus zygotes was taken within a few minutes of fertilization. Let’s contrast that with a photo of a brand new urchin zygote:

Egg of purple sea urchin (Strongylocentrotus purpuratus) fertilized by sperm from a red urchin (Mesocentrotus franciscanus)
30 December 2016
© Allison J. Gong

See? No polar bodies!

All of this is to explain why we can’t use the same magic juice to spawn both urchins and stars. Kinda cool when the madness in our method has a biological context, isn’t it?

Getting lucky

Posted on by Allison J. Gong

As with many things in life, catching a swarm of honey bees is all about opportunity and availability. In other words, luck. Bees swarm in the spring, as the nectar flow and lengthening days result in near-exponential population growth within a colony, and the bees run out of space in their hive. Capturing and rehiving a swarm is one of the best ways for a beekeeper to increase the number of hives in her apiary, for a few reasons:

  1. It’s cheap! Darn near free, except for the minor cost of whatever modified box or bucket used to contain the swarm. For example, for a few years we used an ordinary cardboard file box (the type you’d buy for about $2 at any office supply store) with mesh-covered windows as our official swarm catching box. Last year my husband bought a 5-gallon bucket with lid from a hardware store, cut some windows in it and taped on some mesh. It works better than the box, which was falling apart anyways and needed to be replaced. Still super cheap, too.
  2. Swarms come from locally adapted colonies. True, the mother colony that threw the swarm may have originated as a package colony bought from a commercial beekeeper from anywhere in the country, but at the very least it survived the winter here, which hints at potential long-term suitability for this particular location.
  3. Every swarm that is captured by a beekeeper and rehomed in a managed apiary is a swarm that will not turn a neighbor’s home/garage/fence/etc. into a hive. In terms of responsible beekeeping, this is a Really Good Thing™. It is much simpler to relocate a swarm than to remove an established colony from, say, inside the wall of a house. Most homeowners don’t like being told that in order to get rid of the colony of bees that has taken up residence between the studs in a wall, the wall will have to be cut open to make sure that all the bees, wax combs, and honey are removed.
Ye olde swarm-catching bucket

Until this past weekend it had been an unfortunate spring for us as beekeepers. For the first time in our eight years donning the veil we had lost almost all of our hives over the winter; all of the hives at our house had died, and we were down to 1.5 hives at our second apiary. We had also missed out on a couple of swarm calls, which either came in when we couldn’t deal with them or another beekeeper got to the swarm first. One swarm flew off before we arrived to pick them up, ironically as we were on our way down the highway so I could give a talk on beekeeping to the Watsonville Wetlands Watch.

Much of that luck changed this past Saturday, when we got a call about two swarms in a backyard apple tree. Given that it was a sunny morning, we decided to capture the swarms before the scout bees found a new home site and persuaded their sisters to move into it. They were both good-sized swarms, one a bit larger than a basketball and the other about the size of a football.

Two swarms in an apple tree
15 April 2017
© Allison J. Gong

Those streaky blurs in the sky aren’t UFOs or dust streaks on the camera lens; they’re bees in flight.

The swarms were both about 8 feet off the ground, which puts them nicely within reach of an ordinary ladder. We had brought a ladder with us and the homeowner had one as well, so we could catch both of the swarms at the same time. In the spirit of full disclosure: I can’t take any credit for catching these swarms, as I was taking pictures instead of being useful.

Swarm of honey bees in an apple tree
15 April 2017
© Allison J. Gong

Swarm catching is pretty simple when the bees are clustered in a tree like this: You place a box (or bucket or whatever) under the swarm and either shake the bees into the box or cut the branch they’re clustered on and lower that into the box. Shaking tends to send a lot of bees into the air, but as long as the queen ends up in the box the rest of the bees will eventually find their way to her. When they’re all in the box you close it up and take it away.

The “small” swarm captured into a cardboard box
15 April 2017
© Allison J. Gong

The large swarm went into the bucket:

The “large” swarm going into the bucket
15 April 2017
© Allison J. Gong

We brought the swarms to the apiary. The next step was to pour the bees from the box and bucket into their intended hives. And this is where our luck changed. One of the swarms, instead of settling into our Blue hive boxes, took off into the air. This happens sometimes, when for whatever reason the queen flies and all of the workers go with her. If the beekeeper is lucky they land some place accessible and can be recaptured. This swarm gathered very briefly in the poison oak at the top of a dead coffeeberry bush, then flew away across the street. I was unable to see where they were headed.

The good news was that the larger swarm was much more cooperative and remained in the Purple hive where they were dumped. Joining them in this apiary is the Rose hive, which was a split from one of our downtown hives. The weather on Sunday and Monday was cold and rainy, and today was the first day the bees had a chance to get out and fly. Today (Tuesday) we saw them orienting to their new home. We shouldn’t have any rain for the next several days, which will give them lots of time to forage. Swarms are usually primed and ready to go into building mode as soon as they reach their new home, so the queen in our Purple hive can start laying immediately (assuming, of course, that she was the old queen from the mother hive that threw the swarm; if she’s a virgin she’ll have to go on her mating flights first). It’ll be three weeks before we see an increase in the number of bees; in the meantime the population will decline as bees die off due to natural attrition. Thus around mid-May we should start seeing some big orientation events. Fingers crossed!

Ghosts

Posted on by Allison J. Gong

I seem to have a need to keep investigating seastar wasting syndrome (SSWS) and trying to make sense of what I and others see in the field. I think it parallels my morbid fascination with the medieval Black Death. In any case, I’ve devised a plan to continue experimenting with one aspect of the potential recovery of one species, the ochre star, Pisaster ochraceus.

The first step of this plan was to collect a few more stars, which I did back in early March. For the past year or so the stars had been becoming more abundant at certain sites, leading to hope that the populations were beginning to recover and speculation as to whether these individuals were pre-SSWS survivors or post-SSWS recruits. I think they are survivors, because it seems highly unlikely that a star can grow from teensy (a few millimeters in diameter) to hand-sized on a few years. This is what I want to address experimentally in the lab.

The three stars that I collected seemed to adjust well to life in the lab. They all ate well and were crawling around in their tank. Then, last Friday (31 March 2017, to be exact) I checked on the stars as I usually do and was horrified to see this:

Dismembered bits of an ochre star (Pisaster ochraceus)
31 March 2017
© Allison J. Gong

Knowing from experience how quickly this can happen, I’d guess this star had begun ripping itself into pieces in the previous 24 hours. And meantime, its tankmates had stuck themselves to the underside of the cover of the tank. This is not unusual behavior and once I poked them both to make sure they weren’t getting mush I decided not to worry about them for the time being. The important thing was to remove the not-dead-yet pieces of the exploded star and bleach the tank before returning the apparently healthy stars to it.

One of the most horrific aspects of SSWS is that it is both blindingly fast and agonizingly slow. It appears to strike out of the blue, by which I mean that stars can look absolutely fine one afternoon and be torn to bits the next morning. And it’s slow because the individual pieces can live for hours or even days before finally dying.

31 March 2017
© Allison J. Gong

This star broke itself into five pieces. The three pieces of arm had started getting mushy but still responded by sticking harder when I picked them up. That larger section with two arms and the madreporite was actually walking around the bowl. The torn-off pieces were all oozing sperm into the water, so at least I know this individual was a male. Small comfort, that, when I had to bag up the pieces and throw them in the trash.

Being confronted with the specter of SSWS, I wondered exactly what it meant. I’ve never been under the illusion that SSWS goes away entirely. I suspect that it is always present in the wild, possibly at low enough levels that we don’t notice it for decades at a time. Seeing one dead star, which presumably was infected in the field before I brought it into the lab. . . does it mean the plague is rearing its ugly head again? Or is this a one-off that I just happened to catch? There’s only one way to find out, and that is to see if there are more sick stars in the field. So that’s what I did the following two days. I had planned to visit three intertidal sites where I expect Pisaster ochraceus to live, but my concussed brain allowed me to drive to only the two nearest sites.

I went to Natural Bridges on Saturday, where I’d been seeing lots of ochre stars over the past several months. I hadn’t seen a sick star there for years, although at the outbreak of the plague in 2013 the ochre stars disappeared suddenly. In the past couple of years I’d been happy to see lots of healthy hand-sized stars there. Last weekend it seemed I saw fewer stars than I had gotten used to seeing, but none of them were sick. Whew!

Pair of healthy Pisaster ochraceus at Natural Bridges
1 April 2017
© Allison J. Gong

The next day I went to Mitchell’s Cove, where I’d collected those three stars back in March. I did see lots of great-looking stars, some as small as ~6 cm in diameter and others bigger than my outstretched hand.

Trio of healthy Pisaster ochraceus at Mitchell’s Cove
2 April 2017
© Allison J. Gong

But I also saw this:

Arm of a P. ochraceus that was killed by SSWS at Mitchell’s Cove
2 April 2017
© Allison J. Gong

This is all that remains of an ochre star that apparently succumbed to SSWS. No other body parts are visible in the vicinity, and this arm bit was barely hanging on to the rock. Given how quickly stars can disintegrate when SSWS hits, this one probably began showing symptoms the previous day, while the tide was in and nobody would have seen it. And who knows how many other stars got sick and died without anybody noticing.

The take-home message is that I need to not let SSWS fall off my mental radar. I hope to god that my six remaining P. ochraceus in the lab remain healthy and that I can spawn them in a couple of weeks. I’ve obtained from a friend some small dishes seeded with food that tiny juvenile stars may be able to eat. I’m not too worried about getting through the larval development stage, although I probably shouldn’t get too cocky about that. In any case, it’s the post-larval juvenile survivorship that I’m really interested in. This year I don’t have Scott to help me with the husbandry and data collection. I will instead be working with another colleague, Betsy. We have a spawning date at the end of April, when the next phase of my ongoing SSWS investigation will begin.

They deserve a prettier name than “rockweed”

Posted on by Allison J. Gong

As spring arrives in full force, the algae are starting to come back in the intertidal. The past two mornings I went out on the low tides to look for something very specific (which I did find–more on that later) and noticed the resurrection of the more common red algae. So early in the season the algal thalli are nice and clean, not yet having been fouled or munched. And, like all babies, they’re pretty dang cute.

Here’s a little clump of Endocladia muricata, a red alga with the common name ‘scouring pad alga.’ I’ve also heard it referred to as ‘pubic hair alga,’ by a former instructor of marine botany who shall remain nameless.

Endocladia muricata growing on the test of the large barnacle Tetraclita rubescens, at Natural Bridges
1 April 2017
© Allison J. Gong

What I tried, and failed, to capture in this photo is that the strands have little thornlike extensions that give them the texture of . . . a scouring pad. Here’s a better picture of a larger clump, and if you squint you might be able to see what I’m talking about.

Endocladia muricata
1 April 2017
© Allison J. Gong

And here’s another baby red, this gorgeous little piece of Plocamium. When they’re young like this the branching structure is easier to see. And isn’t that color splendid? Especially with the green of the fresh young surfgrass.

A baby Plocamium, growing among the surfgrass Phyllospadix scouleri
1 April 2017
© Allison J. Gong

What I was really thinking about this morning were the morphological similarities that can make it very difficult to distinguish between different species. For example, there are three species of rockweeds that are common around here: Fucus distichus, Silvetia compressa, and Pelvetiopsis limitata. Rockweeds are brown algae but are usually olive-green in color, and live in the high mid-intertidal above the mussel zone. In some places all three species occur together. Fucus (see below) is easy to recognize because its blades are wider and somewhat straplike, with prominent midribs. When Fucus is reproductive the tips of the blades become swollen and full of a gooey mucilage, which contains the gametes. There are other interesting things about sex in Fucus, and at some point I may address those in a later post.

Fucus distichus, a rockweed, at Franklin Point
17 July 2017
© Allison J. Gong

The other rockweeds, Silvetia and Pelvetiopsis, are a lot more difficult to distinguish. They both have less straplike blades. They share a generalized dichotomous branching pattern, but in neither is it as consistent as it is in Fucus.

Pelvetiopsis limitata at Mitchell’s Cove
2 April 2017
© Allison J. Gong
Silvetia compressa at Mitchell’s Cove
2 April 2017
© Allison J. Gong

This morning these two specimens were growing side by side. In terms of scale the overall length of Silvetia is about twice that of Pelvetiopsis. Keeping that in mind, what you can’t tell from these photos is that Silvetia is also coarser and stiffer, like pasta that is about a minute short of being cooked al dente–not hard, but still more firm that you’d probably like it to be. Pelvetiopsis, on the other hand, is rather soft and much more flexible.

If I were to ask you to contrast these organisms based solely on the photos above, you might say that Silvetia looks somewhat less orderly than Pelvetiopsis. And you would be right! The almost-but-not-quite-dichotomous branching in Silvetia doesn’t always occur in the same plane, resulting in a thallus that doesn’t lie flat. Look at this:

Silvetia compressa at Mitchell’s Cove
2 April 2017
© Allison J. Gong

See how those branches, especially the terminal branches, don’t all come off in the same direction? That’s what I mean. A cross-section of Silvetia‘s blades would be somewhere between flat and cylindrical, also contributing to the tendency of this thallus not to lie flat. This means that when you press it it does get a little mashed looking.

Pelvetiopsis, on the other hand, is a much more regular beast. The blades are distinctly linear in cross-section and generally branch in one plane. One other thing to note is that in Pelvetiopsis the terminal branch tips are very short relative to the overall thallus length compared to those of Silvetia.

Blade tips of Pelvetiopsis limitata
2 April 2017
© Allison J. Gong

A fair question to ask is: How can you tell the difference between a baby Silvetia and a full-grown Pelvetiopsis? Absolute size might not be a useful characteristic, but the other morphological traits are. The branching orientations and overall blade shapes are fairly consistent throughout the size range for each species. Consistent enough, at least, to make a good gut-level first ID guess.

I wanted to write about this because I saw the organisms, checked them off in my head, and then backed up a bit. I found myself second-guessing my instincts when it came to identifying these specimens. I mean, I know these organisms. Or, I think I do. It’s frustrating to look at the creatures I see regularly in the intertidal, organisms whose names I learned many years ago (even through the inevitable taxonomic name changes), and say to myself, “Wait a minute; is that right?” This led me to seriously consider these two rockweed species and evaluate what I really know about each of them. How do I know that one specimen is Pelvetiopsis, when it looks a hell of a lot like a baby Silvetia? I think this unusual self-doubt has to do with post-concussion syndrome. For the past several months I’ve known that words fly out of my mind as I’m trying to recall them. Why not names as well? At this stage in my recovery I’m supposed to be slowly challenging my brain as well as continuing to rest it. Finding that balance has been tricky. In a few weeks I will have my early morning low tides back. It will be easier for me to drive to intertidal sites then, and I’m going to use tidepooling as therapy. It has been good for my soul in the past, and I hope that it will also be good for my brain in the near future.

The hunt concludes

Posted on by Allison J. Gong

Day 3 (Saturday 25 March 2017): Highway 25

We spent our second night on the coast in Morro Bay and came home via Highway 25. I would have enjoyed a drive up the coast, but given the road closures in Big Sur that wasn’t a possibility. Highway 25, however, proved to be a very pretty drive. It was nice to see wildflowers closer to home, too.

Almost all of the hills sported bright yellow patches, some denser than others. At first I thought they were goldfields, but as we got closer I could see that the color was too bright and lemony to be goldfields, and the plants proved to be wild mustard (Sinapis arvensis). Mustard is widely considered a weed in California. Its native habitat is the Mediterranean basin, and one hypothesis is that it arrived in California with the Franciscan friars who established missions up and down the state. Mustard is one of the first plants to bloom every spring, and it covers hillsides, agriculture fields, and the side of the road.

Scenery along Highway 25
25 March 2017
© Allison J. Gong
Scenery along Highway 25
25 March 2017
© Allison J. Gong
Highway 25
25 March 2017
© Allison J. Gong

For the first time in several years the oak trees appear to be flourishing this spring. There was a lot of rain this past rainy season, and it’s such a relief to see the trees coming back to life. I’d forgotten what it is like to see so much green in a California landscape. I mean, just look!

Oak trees along Highway 25
25 March 2017
© Allison J. Gong

Unfortunately for us, most of the land through which Highway 25 winds is private owned, which means we couldn’t just wander off on some back road to get closer to the wildflowers. We did happen upon some lupines which were growing conveniently along the side of the road. These were the big purple bush-type lupines. They were not growing in any kind of park or protected area, so I tossed a couple of sprigs into the plant press.

Lupine (Lupinus sp.) along Highway 25
25 March 2017
© Allison J. Gong
25 March 2017
© Allison J. Gong

By this time the light was fading as the sun began to set behind the western hills, so we headed home. I made it through three days of riding in the car without having a panic attack, which is much better than my concussed brain could have managed a few months ago. All in all it was a great trip, made even better because we got to spend some time with friends and family. These superblooms don’t occur every year, and I’m very glad that I was able to see some of this one.

If you’re considering making a trip to see the wildflowers in the desert areas of southern California, stop thinking about it and just go! If you can spare even a single night away, you will see some awesome displays of Nature’s majesty. And it won’t last much longer, so go now. Don’t worry so much about actual destinations; just keep your eyes open for blooms wherever you can see them and be prepared to travel off the beaten path, because the flowers could be anywhere.

The hunt resumes

Posted on by Allison J. Gong

Day 2 (24 March 2017): Tehachapi, Antelope Valley, and Wind Wolves

We spent the night in Bakersfield and the next morning (24 March 2017) headed up over Tehachapi Pass and headed into Antelope Valley.

It had been many years since I’d driven over Tehachapi Pass, and I didn’t remember ever having seen Joshua trees before. Maybe I was always sleeping on that part of the trip. Once we got past the windmills at the top of the pass–most definitely Not Good for my concussed brain–and started descending into the valley there were Joshua trees all over the place! So cool! And with this year being the 30th anniversary of U2’s best (in my opinion) album, how appropriate.

Joshua trees (Yucca brevifolia) in the Tehachapi Mountains
24 March 2017
© Allison J. Gong

To my admittedly inexperienced eye, Joshua trees are the symbols of the Mojave Desert, as the saguaro is the symbol of the Sonoran Desert. None of the Joshua trees that we saw at Tehachapi were blooming, although I heard from a friend that they were in bloom slightly farther south at Lancaster.

Continuing on, we drove through the desert scrubbiness and eventually could see orange splashed onto the distant hills. We stopped to pick up sandwiches at a corner market and then headed towards the Antelope Valley Poppy Reserve. And bang! all of a sudden we were in the poppy fields.

California poppies (Eschscholzia californica) in Antelope Valley
24 March 2017
© Allison J. Gong

California’s state flower grows as either a perennial or an annual, depending on how much water it receives. In desert areas in the south it behaves like an annual, whereas in moister areas along the coast and in gardens it can come back as a perennial. There are several subspecies of E. californica, each adapted to a particular habitat within the state. Blossom color varies from a golden yellow (very similar to that of fiddlenecks, actually) to a deep intense orange.

California poppies (Eschscholzia californica) in Antelope Valley
24 March 2017
© Allison J. Gong

Our intent was to stop at the visitor center of the park and pick up a trail map, but we never got there. We arrived at early mid-day on a Friday, when everybody from Los Angeles showed up, and the line of cars trying to get into the park was backed up almost to the road. Um, no thanks. Besides, we saw all these poppies from the road, and could find places sort of off the beaten track with fewer people tromping around with selfie sticks than would be inside the actual park. Now I’m not one to discourage people from visiting our state parks, but if you decide to go here, try to arrive earlier in the morning on a midweek day. And time your visit for a sunny day, when the poppies will be open.

Poppies (Eschscholzia californica) and goldfields (Lasthenia californica) near the Antelope Valley Poppy Reserve
24 March 2017
© Allison J. Gong
Field of poppies (Eschscholzia californica)
24 March 2017
© Allison J. Gong

And looking up towards the hills we saw pastel paintings. The orange flowers are poppies, I’m guessing that the yellow is goldfields, and the purple is lupines.

And in terms of lupines, Antelope Valley was the best place we visited. When we made plans to come here I had grandiose ideas of capturing that perfect iconic photograph of purple lupines and orange poppies together. You know the one. Unfortunately I think we arrive a week or two early to catch the peak of the lupine bloom. I never did see nice full lush poppies and blooming lupines in the same spot.

We did, however, see several nice lupine bushes in the various washes around the poppy reserve. Honeybees were glad to see them, too.

A deep purple lupine (Lupinus sp.) in Antelope Valley
24 March 2016
© Allison J. Gong
A foraging honeybee checks out the lupine blossom
24 March 2017
© Allison J. Gong

As glorious as the poppies were, we needed to keep moving in order to meet up with friends on the coast. Working our way westward we stopped at the Wind Wolves Preserve, an ecological reserve managed by the Wildlands Conservancy. I had never heard of the place and wasn’t sure what to expect. What I got was a lovely surprise.

There are, of course, no wolves in this part of California. So then, why the name? According to a sign at the head of the wildflower trail, the name refers to the Preserve’s long grasses, which undulate like running animals when the wind blows through them. I wasn’t carrying the tripod with me so I didn’t try to take any video. However, on our way from Antelope Valley we stopped at Tejon Pass, where the wind was blowing pretty well. I took this video there.

It does look like one of those aerial views of a herd of galloping ungulates, doesn’t it? Perhaps not wind wolves, exactly, but at the Preserve it was easy to imagine how the place got its name. The wildflower walk, a bit less than a mile long, winds through rolling hills covered with grasses and dotted here and there with flowers. There were several small groups of people hiking the trail, and it wasn’t uncommon to have them disappear completely from the landscape when they got lost in the grasses as the trail dipped into a small depression.

Wind Wolves Preserve
24 March 2017
© Allison J. Gong
Wind Wolves Preserve
24 March 2017
© Allison J. Gong

No doubt the resemblance to running wolves will be stronger when the grasses are a bit taller.

We were perhaps two weeks ahead of the bloom and most of the flowers were just starting to open up. The overall effect was a cool wash of green dotted here and there with bright splashes of color. There were lupines, of a smaller ground-growing type rather than the bush lupines we had seen in Antelope Valley, and a plant that we had first seen a lot of on the Carrizo Plain, another whimsically named flower called purple owl’s clover (Castilleja exserta). As its scientific name implies, owl’s clover is a member of the paintbrush family of plants.

Purple owl’s clover (Castilleja exserta) and a small, dark lupine (Lupinus bicolor, perhaps) among the grasses at Wind Wolves Preserve
24 March 2017
© Allison J. Gong

And this might well be my favorite photo of the entire trip:

Purple owl’s clover (Castilleja exserta)
24 March 2017
© Allison J. Gong
Horned lark (Eremophila alpestris)
24 March 2017
© Allison J. Gong

We had already seen many familiar and not-so-familiar birds on the trip, and it was at Wind Wolves that I saw my first ever horned lark (Eremophila alpestris). This individual wasn’t very shy at all; it let us approach within 2 meters on the trail before running off ahead to wait for us again. It had such expressive postures, and a curious look on its face. If there hadn’t been a family with small kids behind us on the trail, I could have watched this bird for a long time. But we couldn’t block the trail just because there was an interesting (to us) bird standing in it, so we let the family pass and the lark flew off into the grasses. They are social birds so no doubt it had friends and family of its own to join.

We saw lizards, too, most notably the western side-blotched lizard (Uta stansburiana ssp. elegans). These lizards have very interesting gender expression, depending on color morph: there are three male morphs (orange-throat, yellow-stripe, and blue-throat) and two female morphs (orange-throat and yellow-throat). Sounds crazy, doesn’t it? The female morphs differ in egg-laying strategy. Orange-throat females lay many small eggs and defend territories, while yellow-throat females lay fewer larger eggs and are less territorial.

Western side-blotched lizard (Uta stansburiana ssp.elegans)
24 March 2017
© Allison J. Gong

Work by Barry Sinervo’s group at UC Santa Cruz showed that the three male color morphs also have different reproductive strategies. They are locked in an evolutionary game of rock-paper-scissors: each color can dominate one (but not both) of the other colors. Note that in this context ‘dominate’ doesn’t necessarily mean that one lizard beats up the other, but rather has greater reproductive success than the other. Orange-throats are the most typically testosterone-driven males; they are more aggressive towards other males and control territories containing several females. Yellow-stripe “sneaker” males hang around the edges of an orange-throated male’s territory and sneak copulations with females while the territory holder’s attention is elsewhere. Blue-throats have an intermediate level of aggression; they can defend a single female from other blue-throats and yellow-stripes, but not against an orange-throat. In a nutshell:

  • Orange beats Blue but loses (sometimes) to Yellow
  • Blue beats Yellow but loses to Orange
  • Yellow beats Orange (sneakily) but loses to Blue

Pretty dang cool, isn’t it?

Next installment: The voyage home

The hunt continues

Posted on by Allison J. Gong

Day 1 (Thursday 23 March 2017) cont’d.: Carrizo Plain National Monument

The Carrizo Plain is an enclosed grassy plain in the southernmost “toe” of San Luis Obispo County, lying between the Temblor Range to the northeast and the Caliente Range to the southwest. Its average elevation is about 700 meters (2200 feet). The main geological features of the plain are a seasonal lake that receives water from both mountain ranges, and the San Andreas Fault, which runs along the northeast edge of the plain up against the aptly named Temblor Range.

Topo map of the Carrizo Plain

For most of the year the Carrizo Plain is hot, dry, and dusty. For a few weeks in the spring, especially if a decent amount of winter rain has fallen, the Plain explodes with color. As in most of the state the dominant color of the flowers is yellow, and the goldfields (Lasthenia californica) grow in huge swaths. Although it is always fun to focus on individual flowers, which I will do later, at the Carrizo Plain the focus is on the landscape.

Soda Lake Road bisects the Carrizo Plain and passes through so many stunning vistas that it is hard to decide where to look. The eye travels from the side of the road, across Soda Lake, and up against the Temblor Range hills and sees amazing splotches of color. It’s quite a spectacular display of natural beauty. Well, there’s also the humongous solar farm at the northwest corner of the lake, but let’s pretend we don’t see it, shall we?

View across Soda Lake Road to the Temblor Range hills
23 March 2017
© Allison J. Gong

In only a few weeks the entire landscape will have transformed from this lush green and yellow to unrelenting dusty brown.

Carrizo Plain
23 March 2017
© Allison J. Gong
Panoramic view of Soda Lake
23 March 2017
© Allison J. Gong
Reflection on Soda Lake 
23 March 2017
© Allison J. Gong

And now let’s get up close and personal with some of the flowers. As mentioned above the goldfields were very common. I did not see any tidy tips on the Plain, although of course that doesn’t mean they weren’t there. One of the most abundant flowers on the Plain is fiddleneck (Amsinckia menziesii), which was just beginning to bloom.

Fields of fiddlenecks (Amsinckia menziesii) on the Carrizo Plain
23 March 2017
© Allison J. Gong
Young fiddleneck (Amsinckia menziesii) blossoms
23 March 2017
© Allison J. Gong

In a couple of weeks the inflorescences will be longer and curled into the shape that gives them their common name, and the overall color of the landscape will shift from the brighter yellow of goldfields to a softer golden shade. Wherever the fiddlenecks occur they are extremely abundant. According to what I’ve read about this plant, later in the season its seeds will be a major food source for seed-eating birds such as finches and sparrows. I don’t remember seeing any finches when we were there, but we did see several white-crowned sparrows flitting about on the tops of the sagebrush.

Baby blue eyes (Nemophila menziesii)
23 March 2017
© Allison J. Gong

Fortunately for the retinas of human visitors, the flowers were not all yellow. Along Shell Creek Road and at the Carrizo Plain there were two types of blue or purple flowers. The bluer of the two, baby blue eyes (Nemophila menziesii) occurred both in small patches on the flats and in big carpets on the hillsides. The bluish patch in the photo of fiddlenecks on the hills (up the page a bit) are all baby blue eyes.

The Great Valley phacelia (Phacelia ciliata) is a delicate, periwinkle-colored flower that contrasts beautifully with the golden orange of fiddlenecks. We saw it scattered here and there, and while it wasn’t uncommon it never seemed to occur in large patches in the Soda Lake area.

Great Valley phacelia (Phacelia ciliata) and fiddleneck (Amsinckia menziesii)
23 March 2017
© Allison J. Gong

Continuing along past Soda Lake we passed hillsides covered with brilliant yellow and purple flowers. In this area of the Carrizo Plain the phacelia did form larger patches, although they were still not as dense as either the fiddlenecks or the goldfields.

Goldfields (Lasthenia californica, background) and Great Valley phacelia (Phacelia ciliata, foreground)
23 March 2017
© Allison J. Gong

And in case you think there might not have been enough yellow in the landscape: BAM!

Goldfields (Lasthenia californica)
23 March 2017
© Allison J. Gong

Next installment: Antelope Valley and the Wind Wolves Preserve.

The hunt begins

Posted on by Allison J. Gong

RAIN + SUN = WILDFLOWERS

That’s one of the truisms of life in a Mediterranean climate such as ours. The official water year as measured by NOAA runs from 1 October through 30 September, and along the central/northern California coast most of the rain falls from December through March. The rest of the year, April through the summer and most of the fall, is the long dry season.

Plants that have evolved to live in Mediterranean climates respond quickly to water when it is available. For many annual plants, this means rapid growth in the spring when the soil begins to warm up and the days are getting longer, followed by a burst of flowering as the plants complete their life cycles. Once the rain stops falling there is no water except what is stored in the ground, out of reach for most shallow-rooted plants. The annuals take advantage of the short window between the end of the heaviest rains and the onset of yearly drought to bloom and have sex (i.e., set seed). From 2011-2015 there was moderate to severe drought through most of the state and spring wildflower blooms were anemic and less-than-spectacular. In April 2016, after the El Niño rains of the previous season, some friends and I went down to southern California to check out the bloom. We had made a day trip of it, and it was a very long day that didn’t allow for much meandering or poking around. This year we had read from several sources that the heavy winter/early spring rains followed by sunshine would result in a very strong superbloom and managed to squeeze in a 3-day trip, which allowed us to visit more places and change our plans at the last minute if we heard about something interesting to see.

Day 1 (Thursday 23 March 2017): Shell Creek Road 

Shell Creek road is the little road that runs north-south from the hamlet of Shandon to the northwest corner of the Carrizo Plain. The roadbed runs along a little creek that meanders through rolling hills dotted with oak trees. It is really pretty when covered with grasses and wildflowers in the spring, although it will be hot, dusty, and brown for half the year. This is where we caught our first glimpses of the superbloom in action.

Wildflower bloom along Shell Creek Road in San Luis Obispo County
23 March 2017
© Allison J. Gong
Wildflower bloom along Shell Creek Road in San Luis Obispo County
23 March 2017
© Allison J. Gong

The dominant color of the landscape is yellow. A quick thumb-through of any western wildflowers field guide will confirm this. We do have a plethora of yellow flowers in California. In fact, one of the hypothesized reasons California is referred to as “the golden state” is the flood of yellow that carpets hills and valleys in the springtime. The other hypothesis I’ve heard is that “golden” refers to the color of the hills during the long dry season. Both of these seem feasible to me.

So who’s responsible for all this yellow?

The main culprit is the aptly named goldfields (Lasthenia californica). They are very common members of the daisy family, the Asteraceae, and are found in most regions of the state except at higher elevations in the Sierra Nevada.

Goldfields (Lasthenia californica) along Shell Creek Road in San Luis Obispo County
23 March 2017
© Allison J. Gong

Another goldfield look-alike is a flower with the strange common name of Bigelow’s tickseed. Its real name is Leptosyne bigelovii. It’s a California endemic, found only in the southern half of the state. I looked at a lot of photos, mine and others’, trying to learn how to distinguish between the tickseed and goldfields, and hope I have it right.

This is Bigelow’s tickseed:

Bigelow’s tickseed (Leptosyne bigelovii) along Shell Creek Road in San Luis Obispo County
23 March 2017
© Allison J. Gong

See the differences in flower morphology? I’ve got samples of each species (I hope!) drying in the plant press, and should be able either to confirm or refute my identifications once I can take a look at them. It’s always a good idea to calibrate my intuition whenever I can.

A third yellow flower, which occurs throughout the coastal mountains but we saw only at Shell Creek Road, is the delightfully named coastal tidy tips (Layia platyglossa). This is the kind of common name that makes me smile. You’ll see why.

Coastal tidy tips (Layia platyglossa) along Shell Creek Road in San Luis Obispo County
23 March 2017
© Allison J. Gong

Perhaps the tidy tips form large dense patches more readily at other locations, but this year we saw them mostly interspersed among the goldfields. They are conspicuous enough that I think I would have noticed them if I’d seen them last year. From a macro perspective the white petal tips lend a more creamy yellow color to the landscape, compared to the unrelenting blinding yellow of the goldfields. I had never seen them before, and there’s something about those white tips that just tickles my fancy. How could I not be enchanted?

Goldfields (Lasthenia californica) and coastal tidy tips (Layia platyglossa) along Shell Creek Road in San Luis Obispo County
23 March 2017
© Allison J. Gong

As lovely as it was, Shell Creek Road was only the first location we wanted to visit that day. Our ultimate destination was the Carrizo Plain National Monument, in southeastern San Luis Obispo County. More about that shortly.

Complexity in small packages

Posted on by Allison J. Gong

Last week I went up to Davenport to do some collecting in the intertidal. The tide was low enough to allow access to a particular area with two pools where I have had luck in the past finding hydroids and other cool stuff. These pools are great because they are shallow and surrounded by flat-ish rocks, so I can lie down on my stomach and really get close to where the action is. At this time of year the algae and surfgrasses are starting to regrow; the surface of the pools was covered by leaves of Phyllospadix torreyi, the narrow-leafed surfgrass.

Parting the curtain of Phyllospadix leaves to gaze into the first pool I was pleasantly surprised to find this. What does it look like to you?

Aglaophenia latirostris at Davenport Landing
8 March 2017
© Allison J. Gong

There are actually two very different organisms acting as main subjects in this photo. The pink stuff is a coralline alga, a type of red alga that secretes CaCO3 in its cell walls. Coralline algae come in two different forms: one is a crust that grows over surfaces and the other, like this, grows upright and branching. Because they sequester CaCO3, corallines are likely to be affected by the projected increase of the ocean’s acidity due to the continued burning of fossil fuels. Ocean acidification is one of the sexy issues in science these days, and although it is very interesting and pertinent to today’s world it is not the topic for this post. Suffice it to say that changes in ocean chemistry are making it more difficult for any organisms to precipitate CaCO3 out of seawater to build things like shells or calcified cell walls.

It’s the tannish featherlike stuff in the photo that I was particularly interested in. At first glance the tan thing looks like a clump of a very fine, fernlike plant. It is, however, an animal. To be more specific, it is a type of colonial cnidarian called a hydroid. I love hydroids for their hidden beauty, not always visible to the naked eye, and the fact that at first glance they so closely resemble plants. In fact, many hydroid colonies grow in ways very similar to those of plants, which has often made me think that in some cases the differences between plants and animals aren’t as great as you might assume. But that’s a matter for a separate essay.

I collected this piece of hydroid and brought it back to the lab. The next day I took some photos. To give you an idea of how big the colony is, the finger bowl is about 12 cm in diameter and the longest of these fronds is about 3 cm long.

Colony of the hydroid Aglaophenia latirostris
9 March 2017
© Allison J. Gong

And here’s a closer view through the dissecting scope.

The colonial hydroid Aglaophenia latirorostris
9 March 2017
© Allison J. Gong

Each of the fronds has a structure that we describe as pinnate, or featherlike–consisting of a central rachis with smaller branches on each side. This level of complexity can be seen with the naked eye. Zooming in under the scope brings into view more of the intricacy of this body plan:

Close-up view of a single frond of Aglaophenia latirostris, showing feeding polyps and two gonangia
9 March 2017
© Allison J. Gong

At this level of magnification you can see the anatomical details that cause us to describe this animal’s structure as modular. In this context the term ‘modular’ refers to a body that is constructed of potentially independent units. A colony like this is built of several different types of modules called zooids, some of which are familiarly referred to as polyps. Each zooid has a specific job and is specialized for that job; for example, gastrozooids are the feeders, while gonozooids take care of the sexual reproduction of the colony. In this colony of Aglaophenia each of these side branches consists of several stacked gastrozooids, which you can see as the very small polyps bearing typical cnidarian feeding tentacles. Aglaophenia is a thecate hydroid; this means that each gastrozooid sits inside a tiny cup, called a theca, into which it can withdraw for protection. Those larger structures with pinkish blobs inside are called gonangia. A gonangium is a modified gonozooid, found in only thecate hydroid colonies, that contains either medusa buds or other reproductive structures called gonophores.

Pretty complicated, isn’t it? Who would expect such a small animal to have this much anatomical complexity?

In the second pool I found an entirely different type of hydroid. At first glance this one looks more animal-like than Aglaophenia does, although it is still a strange kind of animal. This is Sarsia, one of the athecate hydroids whose gastrozooids do not have a protective theca. It might be easier to think of these and other athecate hydroids (such as Ectopleura, which I wrote about here and here) as naked, with the polyps not having anywhere to hide.

Colony of the athecate hydroid Sarsia sp.
9 March 2017
© Allison J. Gong

Each of these polyps is about 1 cm tall. The mouth is located on the very end of the stalk. The tentacles, not quite conforming to the general rule of cnidarian polyp morphology, do not form a ring around the mouth. Instead, they are scattered over the end of the stalk.

Here’s a closer view:

Colony of the athecate hydroid Sarsia sp.
9 March 2017
© Allison J. Gong

In the hydroid version of Sarsia, the reproductive gonozooids are reduced to small buds that contain medusae. You can see a few round pink blobs in the lower right of the colony above; those are the medusa buds.  The medusae are fairly common in the local plankton, indicating that the hydroid stage is likewise abundant. Here’s a picture of a Sarsia medusa that I found in a plankton tow in May 2015.

Medusa of the genus Sarsia
1 May 2015
© Allison J. Gong

The medusa of Sarsia is about 1 mm in diameter and has four tentacles, which usually get retracted when the animal is dragged into a plankton net. Sometimes, if the medusa isn’t too beat up, it will relax and start swimming. I recorded some swimming behavior in a little medusa that I put into a small drop of water on a depression slide. It refused to let its tentacles down but you might be able to distinguish four tentacle bulbs.

There’s a lot more that I could say about hydroids and other cnidarians. They really are among the most intriguing animals I’ve had the pleasure to observe, both in the field and in the lab. I’ve always been fascinated by their biphasic life cycle, with its implications for the animals’ evolutionary past and ecological present. Perhaps I’ll write about that some time, too.