Skip to content

A few days ago I was in the intertidal with my friend Brenna. This most recent low tide series followed on the heels of some magnificently large swells and it was iffy whether or not we'd be able to get out to where we wanted to do some collecting. Our first day we went up to Pistachio Beach, just north of Pigeon Point, where the rocky intertidal is bouldery and protected by some large rock outcrops.

Pigeon Point lighthouse, viewed from Pistachio Beach.
27 January 2017
© Allison J. Gong
27 January 2017
© Allison J. Gong

So while the swell was indeed really big, we were pretty well protected in the intertidal. The Seymour Center has a standing order for slugs, hermit crabs, and algae. I was easily able to grab my limit (35) of hermit crabs over the course of the afternoon, and while it's too early in the season for the algae to do much I had my sluggy friend with me to take care of finding nudibranchs, which left me free to let my attention wander as it would.

Codium setchellii at Pistachio Beach.
27 January 2017
© Allison J. Gong

The very first thing to catch my eye as we go out there was the coenocytic green alga Codium setchellii, which I wrote about last time. I've seen and collected C. setchellii from this site before, but don't remember seeing it in such large conspicuous patches. I need to review what I learned about the phenology of various intertidal algae, but here's a thought. Maybe Codium is an early-season species that gets outcompeted by the plethora of fast-growing red algae later in the spring. Red algae were present at Pistachio Beach but not in the lush (and slippery!) abundance that I'll see in, say, June. I'm willing to bet that Codium will be less abundant in the next few months.

Leptasterias sp. at Pigeon Point.
24 April 2016
© Allison J. Gong

In my experience, the six-armed stars of the genus Leptasterias have always been the most abundant sea stars on the stretch of coastline between Franklin Point and Pescadero. Even though they are small--a monstrously ginormous one would be as large as the palm of my hand--they are very numerous in the low-mid intertidal. I've seen them in all sorts of pinks and grays with varying amounts of mottling. Alas, I don't know of any really reliable marks for identifying them to species in the field.

Unlike other familiar stars, such as the various Pisaster species and the common Patiria miniata (bat stars), which reproduce by broadcast spawning their gametes into the water, Leptasterias is a brooder. Males release sperm that is somehow acquired by neighboring females and used to fertilize their eggs. There isn't any space inside a star's body to brood developing embryos, so a Leptasterias female tucks her babies underneath her oral surface and then humps up over them. Leptasterias also humps up when preying on small snails and such, so that particular posture could indicate either feeding or brooding.

Here's a Leptasterias humped up on a rock, photographed last spring:

Leptasterias sp. at Pigeon Point.
5 May 2016
© Allison J. Gong

The only way to tell if a Leptasterias star is feeding or brooding is to pick it up and look at the underside. I did that the other day and saw this:

Brooding Leptasterias sp. star at Pistachio Beach.
27 January 2017
© Allison J. Gong

Those little orange roundish things are developing embryos. While the mother is brooding she cannot feed, and can use only the tips of her arms to hang onto rocks. Don't worry, I replaced this star where I found her and made sure she had attached herself as firmly as possible before I left her. In a few weeks her babies will be big enough to crawl away and she'll be able to feed again.

Looks like the reproductive season for Leptasterias has begun.


The next day Brenna and I went to Davenport, again hoping to get lucky despite another not-so-low tide and big swell.

Davenport Landing Beach and adjacent rocky areas.
© Google Earth

Davenport Landing Beach is a popular sandy beach, with rocky areas to the north and south. The topography of the north end is quite variable, with some large shallow pools and lots of vertical real estate to make the biota very diverse and interesting. The big rocks also provide shelter from the wind, a big plus for the intrepid marine biologist who insists on going out even when it's crazy windy. The southern rocky area is very different, consisting of flat benches that slope gently towards the ocean, with comparatively little vertical terrain. The southern end of the beach is always more easily accessible, which is why I almost always go to the north. But this day the north wasn't going to happen. The winter storms had washed away at least a vertical meter of sand between the rock outcrops. That and the not-so-low tide combined for conditions that made even getting out to the intended collecting site a pretty dodgy affair. So Brenna and I trudged across the beach to the south.

28 January 2017
© Allison J. Gong

Along the way we saw lots of these thumb-sized objects on the beach. At first glance they look like pieces of plastic, but after you see a few of them you realize that they are clearly (ha!) gelatinous things of biological origin. They are slipper-shaped and you can stick them over the ends of your fingers. They have a bumpy texture on the outside and are smooth on the inside.

Any guesses as to what they are?

Pseudoconch of Corolla spectabilis, washed up on Davenport Landing Beach.
28 January 2017
© Allison J. Gong

These funny little things are the pseudoconchs of a pelagic gastropod named Corolla spectabilis. What is a pseudoconch, you ask? If we break down the word into its Greek roots we have 'pseudo-' which means 'false' and 'conch' which means shell. Thus a pseudoconch is a false shell. In this case, 'false' refers to the fact that this shell is both internal (as opposed to external) and uncalcified.

The animal that made these pseudoconchs, Corolla spectabilis, is a type of gastropod called a pteropod (Gk: 'wing-foot'). Pteropods are pelagic relatives of nudibranchs, sea hares, and other marine slugs. They are indeed entirely pelagic, swimming with the elongated lateral edges of their foot. Like almost all pelagic animals, Corolla has a transparent gelatinous body. Even their shell is gelatinous, rather flimsier than most shells, but it serves to provide support for the animal's body as it swims.

You can read more about Corolla spectabilis and see pictures and video here.

Why, you may be wondering, do the pseudoconchs of C. spectabilis end up on the beach, and where is the rest of the animal? The body of Corolla and other pteropods is soft and fragile. When strong storms and heavy swells seep through the area, the water gets churned up and pteropods (and other pelagic animals) get tossed about and shredded. This leaves their pseudoconchs to float on currents until they are either themselves demolished by turbulence or cast upon the beach. Corolla is commonly seen in Monterey Bay, and it is not unusual to find their pseudoconchs on the beaches after a series of severe storms.

Brenna and I were wondering if we could preserve the pseudoconchs somehow. I took several back to the lab and tried to dry them, thinking that they might behave like Velella velella does when dried. Unfortunately, the next day they had shriveled into unrecognizable little blobs of dried snot, and the day after that they had disintegrated completely into piles of dust. Maybe drying them more slowly would work. Something to consider the next time I run across pseudoconchs in the sand.

1

A few days ago I told my friend Brenna that I'd hunt around in the marine lab for a bit of a green alga that she wants to press. I had a pretty good idea of where to look, only the animals I'd seen it on had been removed from the exhibit hall. I asked for and got permission to examine the animals behind the scenes. And fortunately I had remembered correctly, and I was able to pick off some nice clumps of dark green stuff.

Bryopsis corticulans is a filamentous green alga. It grows to about 10 cm in length and is a dark olive color. When emersed it sometimes looks almost black. I've seen it in the intertidal in a few places, where at low tide it resembles nothing so much as a shapeless slime. It's very difficult to see the beauty of organisms when they're out of their natural element, which in this case is water.

B. corticulans emersed during low tide at Mitchell's Cove.
8 June 2016
© Allison J. Gong

But see how pretty it is when submerged?

Bryopsis corticulans
23 January 2017
© Allison J. Gong

One of the reasons I love the algae is their very inscrutability. I enjoy discovering the beauty of organisms that, at first glance, don't look like much. Many of the filamentous algae, both the greens and the reds, have a delicate structure that requires close examination to be appreciated. Fortunately, I have access to microscopes, so close examination is very easy.

The thallus of B. corticulans is relatively simple, consisting of a bipectinate arrangement of filaments.

Apical tip of Bryopsis corticulans.
23 January 2017
© Allison J. Gong

Here's a closer view:

Thallus of Bryopsis corticulans.
23 January 2017
© Allison J. Gong

This is a shot of the main axis and side filaments. The small green blobs are chloroplasts. One thing to notice is that there are no crosswalls separating any of the filaments. That's because the thallus is coenocytic, essentially one large cell with a continuous cytoplasm. Coenocytic cells are common in fungi, the red and green filamentous algae, and a few animals. In animals, coenocytic cells are often referred to as syncytial. They can arise in one of two ways: (1) adjacent cells fuse together; or (2) nuclear replication occurs as usual during normal mitosis but cytokinesis (division of the cytoplasm) does not. However the syncytium arises, it can result in very large cells. Even though B. corticulans itself is a small organism, some algae in the Bryopsidales consist of single cells that can be over 1 meter long!

Sometimes things that appear simple at first glance conceal a deeper complexity when you look more closely.

It has been almost three and a half years since I first documented seastar wasting syndrome (SSWS) in the lab. Since then many stars have died, in the field and in the lab, and more recently some species seem to be making a comeback in the intertidal. This circumstantial evidence may not be reason enough to conclude that the epidemic is over, but I think there is reason to be hopeful. Any disease outbreak eventually runs its course, and despite its death toll there are always at least some survivors. And I have an individual star that was very sick but seems to be recovering.

In September of 2015 one of my bat stars (Patiria miniata) developed the first tell-tale lesion of SSWS on its aboral surface. At the time the lesion was small (less than 10 mm in diameter) and superficial. Knowing that SSWS starts with minor symptoms and rapidly progresses to something horrific within a day or so, I wanted to keep an eye on this star. It held the same morbid fascination as a car accident or any other impending catastrophe.

5 September 2015

Bat star (Patiria miniata) with small aboral lesions.
4 September 2015
© Allison J. Gong
Dermal lesion on the aboral surface of a bat star (P. miniata).
5 September 2015
© Allison J. Gong

24 November 2015

By November 2015 the main lesion hadn't grown much but a few others had developed. The star still wasn't acting sick and was eating every once in a while, although it occasionally ignored the food that I offered.

Bat star (P. miniata) with aboral lesions.
24 November 2015
© Allison J. Gong

So far, so good. I was thinking that the star doesn't look too much worse, so maybe it wouldn't keep getting sicker. I checked on it regularly, offered food a few times a week, and left it alone.


4 May 2016

Several months later I noticed that the first lesion had gotten much deeper. The outer dermal layers had been completely compromised, exposing the animal's internal organs (gonad and digestive caecum) to the external environment. This was bad, very bad. Even in stars, internal organs are supposed to be internal, except when stars extrude their stomachs to feed.

Bat star (P. miniata) with deep aboral lesion.
4 May 2016
© Allison J. Gong
Lesion on aboral surface of a bat star (P. miniata). Note the internal structures that are exposed to the surrounding seawater.
4 May 2016
© Allison J. Gong

This was the point in time when things started going south. The star lost the ability to maintain its internal turgor pressure and became lethargic and floppy. It stopped eating, or even responding to food. It spent most of its time in a corner of the seawater table where it lives, although a few times I saw it wrapped around one of the hoses that feeds the table. However, its body never started disintegrating the way I'd seen with other SSWS victims.


19 January 2017

Fast-forward another several months. About a month ago the sick bat star began perking up a bit when I placed food near the tip of one of the arms. A week later it actually wrapped its arm around the food, and I assume ate it. It has since been eating about once a week, after fasting for at least eight months. I began to think it would recover.

Today I had some time to photograph the star again, and it really appears to be doing much better!

Bat star (P. miniata) with healing lesions.
19 January 2017
© Allison J. Gong

The lesions are apparently healing over; at any rate, the internal organs are no longer exposed to the outside. The body margin between the arms has a few small divots, but they look superficial. Lately the star has been more active, too, cruising around the table instead of hunkering down in a corner. I'm going to keep feeding it to see if it continues to improve.

One of the most remarkable things about many animals with a decentralized nervous system, such as echinoderms and cnidarians, is their ability to regenerate lost parts and repair damage to their bodies. This bat star is a prime example. It has been sick for almost a year and a half now, and for at least half that time it hasn't eaten. Yet it somehow had the metabolic reserves to heal a major wound to its body wall. That's some astounding resilience there. I am very impressed, and you should be, too.

2

Although at this stage it's a close race. Two and a half weeks ago I spawned sea urchins in the lab, setting up several purple urchin crosses with the hope of re-doing the feeding experiment that I lost this past summer when I was on the DL (that's Disabled List, for those of you who don't speak baseball). I was also fortunate enough to set up a hybrid cross, fertilizing purple urchin (Strongylocentrotus purpuratus, or "Purp") eggs with red urchin (Mesocentrotus franciscanus, or "Red") sperm. I would have done the reciprocal hybrid cross (red eggs by purp sperm) as well if I'd gotten any of female red urchins to spawn. However it wasn't really spawning season for the reds, and I consider myself lucky to have persuaded that one male to release some sperm for me.

This is the first time that I've tried to raise the hybrid larvae, although I know it can be done because my colleagues Betsy and John did it many years ago, before I came to the marine lab. All of my larvae are the exact same age and are being raised side-by-side, so I can make direct comparisons between the Purp by Purp crosses and the Purp by Red hybrids. Incidentally, when speaking or writing about a hybrid cross the convention I've adopted is to reference the female parent first, so when I say Purp by Red I mean a Purple eggs fertilized by Red sperm. A Red by Purp hybrid would logically result from red urchin eggs fertilized by purple urchin sperm.

My experience raising sea urchin larvae is that things almost always go well for the first 48 hours or so; most (but not all) of the fertilized eggs develop into embryos and undergo the crucial processes of gastrulation and hatching. In some cultures the hatching rate is close to 100%. After that there's a window of 3-4 days when cultures can crash for no apparent reason, although food availability or quality may be a factor. If the larvae make it past their first week of post-hatching life they generally cruise along until the next danger period which occurs at about 24 days. I change the water in the culture jars and observe the larvae under the microscope twice a week.

Today the larvae are 18 days old. It's a little early for that second mortality period, but some of the Purp by Purp cultures never really took off. The larvae don't seem to be growing or developing as quickly as I'm used to. Perhaps this has to do with lower water temperatures, especially after the prolonged period of high temps in 2014-2015. In any case, two of the four Purp by Purp crosses are doing well and the other two are just hanging in there.

There are two things I can see with the naked eye that give me a heads-up when cultures are crashing: the first sign is an accumulation of debris at the bottom of the jar and the second is an absence of larvae in the water column. The debris can be due to excess food, a build-up of fecal matter (not usually the case, as I'm pretty good at doing the water changes on time), the disintegration of larval bodies, or some combination thereof. If the water column is clear then the culture has already crashed and everybody is dead.

Today one of my jars had crashed. The water column was very clear and there was a lot of fluff at the bottom of the jar. I'd been wondering if I could figure out what the fluff was made of, so I sucked up a bit in a pipet and examined it under the microscope. I thought I'd see dead algal cells or pieces that look like defecated algal cells. This is what I saw:

18 January 2017
© Allison J. Gong

Silly me. I had forgotten that the corpses of pluteus larvae would disintegrate pretty quickly, leaving behind only the skeletal rods. The rods get all tangled together and trap the organic stuff, which is probably a mixture of uneaten and defecated algal cells and the soft tissues of the larval bodies. This explains the clear water column in the jar.

While the Purp by Purp larvae have had mixed success so far, the Purp by Red hybrids have been doing well. From the outset they appeared to be more robust than the Purps, and even though the fertilization rate was only about 50% the post-hatching mortality seems low. The hybrid larvae are also larger than the Purps, and are developing more quickly. In the two photos below the scale bar indicates 100 µm.

Pluteus larva of Strongylocentrotus purpuratus, age 18 days.
17 January 2017
© Allison J. Gong
Pluteus larva of a hybrid cross between S. purpuratus and Mesocentrotus franciscanus, age 18 days.
17 January 2017
© Allison J. Gong

The hybrid larva is about 10% larger than the Purp larva. Other than that they look similar, but to me the hybrid larva seems farther along the developmental process: its arms are proportionally longer and have a more mature look (although I don't have any way to describe that to a naive observer). There's something about the gestalt of the animal that makes me think it's more robust than the Purp individual.

We'll see how the pure Purps and the hybrids do from here on. I actually have the Purp larvae divided up into different feeding treatments, which I may discuss in a future blog post. In the meantime I'm trying to baby the hybrid larvae as much as possible, to maximize their probability of successful metamorphosis in six weeks or so.

Northern California is currently being pummeled by a meteorological phenomenon called an atmospheric river. The storms produced by these "rivers" tend to be warm and can be very wet, such as the Pineapple Express storms that carry atmospheric moisture from Hawai'i to California. The weather station on the roof of our house has recorded 4.26 inches of rain over the past three days, and more will come in the next few days. In addition to the rain, the atmospheric river has brought very strong winds, gusting to 40+ mph. Combined with the saturated ground, winds like this can uproot trees and utility poles. So far we haven't lost power, but are prepared with candles, firewood, and extra water. . . just in case.

Data from our weather station in Santa Cruz, CA.
8 January 2017

I am not a meteorologist, and this is not a blog about weather. I mention all the rain because it brought out the worms. Earthworms, to be more precise.

Earthworms are oligochaete worms in the phylum Annelida, which also contains the polychaetes (marine segmented worms) and hirudineans (leeches). The body plan for annelids is based on segmentation, or metamerism. Let me explain what that means.

Imagine a round water balloon. Now imagine two sets of rubber bands encircling the balloon along perpendicular axes. You'd have something like this:

where the green and red lines indicate different muscle types. Remember that we're discussing a three-dimensional object here. We'll call the red lines circular muscles, and the green lines longitudinal muscles. Now picture in your mind what happens when the circular muscles contract; how does this change the shape of the water balloon? What happens when the longitudinal muscles contract?

An annelid's body consists of many fluid-filled segments, each with its own set of circular and longitudinal muscles. The segments are arranged along the anterior-posterior axis, with the head being located at the anterior end.

Adjacent segments are separated by a layer of tissue called a septum (anatomically speaking, a septum is any tissue that divides a cavity into two or more smaller spaces; think of the septum that divides your nasal cavity into left and right nostrils). An incidental amount of fluid may escape from one segment into the next, but for the most part they function as separate water balloons. Water isn't compressible but is deformable, so contracting muscles around one part of the water balloon simply displaces that water to another part, and the balloon's shape changes. Because each segment in our worm has its own complement of body wall musculature, its shape can be modified independently from that of its neighbors.

Rather than draw up another pedagogical worm, I'll show you a real one. As I mentioned earlier all the recent rains have brought the earthworms out from their burrows. I was out and about myself this afternoon, and took pictures. This is the anterior (front) end of a worm. Not much of a head, is there? Earthworms are poorly cephalized, which makes sense when you consider that they live underground: an animal that spends almost all of its time in complete darkness has no need for eyes, and having sensory organs hanging off the body would impede its burrowing activities.

Earthworm on wet pavement.
8 January 2017
© Allison J. Gong

That pale pink apparently unsegmented bit of worm is the clitellum, a glandular structure used in reproduction. Another feature you can see is the difference in size among all the segments. Some of them are much wider than others. These are the localized deformations. The anterior-most segments are the widest; which type of muscle is contracted in this part of the worm? Which muscles are contracted in the segments immediately in front of the clitellum?

Earthworm on wet pavement.
8 January 2017
© Allison J. Gong

The annelid body plan originally evolved to facilitate burrowing through soft substrates. The fluid in each segment provides a stiffness against which the body wall muscles can contract, and the separation of adjacent segments allows the aforementioned localized deformations. An earthworm burrows by making its front end long and pointy (by contracting the circular muscles), jabbing it into the soil, swelling those anteriormost segments (by relaxing circular muscles and contracting longitudinal muscles), and pulling the rest of the body along. Next time you have a live earthworm at your disposal, watch how it moves either on top of or through the ground.

As you may imagine, while an earthworm's body volume remains constant, its shape varies greatly. This has consequences for internal anatomy as well. For example, an earthworm's gut is essentially a straight tube within a tube; it doesn't have distinct compartments or side chambers as ours does. But it can't really be straight, can it? If the overall body shape of an individual worm can change as much as we see in a burrowing earthworm, it follows that the internal morphology must be equally plastic. This means that the blood vessels and major nerve cord remain functional whether the worm is stretched out or scrunched up. Kinda hard to imagine that in the body of any vertebrates.

Does the title of this post make any sense now?

%d bloggers like this: