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The marine macroalgae are, as a group, the most conspicuous organisms in the intertidal. Yet, most tidepool explorers dismiss them as "seaweeds" and move on to the next thing, which they hope is somehow more interesting. This is akin to visiting the jungles of Brazil and not paying attention to the lush foliage that defines that particular biome. I will admit that, as a zoologist whose primary interest is the marine invertebrates, I have been guilty of this offense. I've also felt guilty about the oversight and thought to myself, "I really should know the algae better." I have no formal training in phycology beyond auditing marine botany labs after I finished graduate school, but I've got the basics down and really have no excuse for the continuation of this gap in my knowledge.

So a couple of years ago I decided to start filling in that gap. I dragged out my marine botany notebook and have slowly been adding to it, building up my herbarium collection at the same time.

The red algae (Rhodophyta) are the arguably the most beautiful of the seaweeds, and inarguably are the most diverse on our coast. Some of them are easy to identify because nothing else looks like them, but many share enough morphological similarity that field IDs can be tricky if not downright impossible. For example, to ID a specimen and distinguish it from a close relative you may need to examine the number, size, and arrangement of cells in a cross-section of a blade. Some species are impossible to identify beyond genus (or even family, in some cases) unless you can look at their reproductive structures, which they might not have at the time they're collected.

One of the most ubiquitous red seaweeds, and one that is easily identified to genus, is Mazzaella. The genus name for this group of species used to be Iridea, which gives a hint as to the appearance of the thalli--many of them are iridescent, especially when wet. The species that I see most often are M. flaccida in the mid intertidal and M. splendens lower down. These species are usually not difficult to tell apart once you get used to looking at them and their respective habitats.

Mazzaella splendens at Whaler's Cove at Pigeon Point
28 June 2017
© Allison J. Gong
Mazzaella flaccida at Natural Bridges
9 July 2017
© Allison J. Gong

Mazzaella splendens is generally a solid brown with sometimes a green or purple cast. It is soft and floppy, and the blades are long (up to 50 cm) and taper to a point. The Marine Algae of California, which we call the MAC, uses the term "lanceolate" to describe this shape. Mazzaella flaccida is green or greenish-purple, sometimes more brownish along the edges; its blades are flexible but a teensy bit crisper than those of M. splendens, and its blades are described as cordate (heart-shaped) or broadly lanceolate.

Got it. That's not too bad, right?

But then you see something like this, and a whole other set of questions comes to mind.

Thalli of Mazzaella flaccida at Natural Bridges
9 July 2017
© Allison J. Gong

Based on habitat alone these are both M. flaccida. The greenish thallus on top looks like textbook M. flaccida, but the lower thallus looks more ambiguous. It has the right size and shape but is the wrong color, and what's up with all those bumps? I brought these thalli back to the lab to examine them more closely. Here are the entries from my lab notebook:

 

 

 

 

 

 

 

Now is the time to bring up the subject of life cycles in red algae. Algae such as Mazzaella alternate through three generations: male and female gametophytes, both of which are haploid; a diploid sporophyte; and a diploid carposporophyte. Here's a diagram that shows how this alternation of three generations works:

Life cycle of some red algae, showing alternation of three generations
© McGraw-Hill

It was easy to see that the bumpy thallus I collected was sexy, while the smooth green thallus was probably not reproductive. Having both thalli in hand, along with the MAC and phycology texts in the lab, I was able to determine that the bumpy brown thallus is actually two generations in one body. So cool! But how does this work? The bumps on the thallus are called cystocarps. In Mazzaella a cystocarp contains the diploid tissue of the carposporophyte surrounded by the haploid tissue of the female gametophyte. Et voilà! Two generations in a single thallus.

Now, what's inside the cystocarp? What does the carposporophyte tissue actually look like? To find out I had to do some microsurgery, first to remove a carpospore (1-1.5 mm in diameter) from the female gametophyte and then to cut it open to see what's inside. What's inside were microscopic diploid carpospores, which grow into the macroscopic sporophyte generation. Forcibly dissected out as they were, they don't look like much, just tiny round cells about 2 µm in diameter.

Carpospores of Mazzaella flaccida
12 July 2017
© Allison J. Gong

The next logical step would be to isolate some of the carpospores and try to grow them up. I wasn't thinking about that at the time and pressed both thalli. However, I do have another female gametophyte with cystocarps that I can investigate further tomorrow. It's probably a fool's errand, as I am not going to bother with sterile media and whatnot. Oh well. Nothing ventured, nothing gained, right?

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Today my Pisaster ochraceus larvae are 10 days old. Although they seemed to be developing slowly, compared to the urchins that I'm more used to, in the past several days they have changed quite a bit. They've also been growing quickly, which makes me think that they're off to a strong start. Of course, there's still a lot of time for things to go wrong, as they have another couple of months in the plankton. However, at this point in time I feel optimistic about their chances.

In the dish under the dissecting scope they swim around like bizarre space ships. All the bits of detritus in the water add to the effect. The only thing missing is the sound effects.

The magnification of my dissecting scope goes up to 40X. To see any details of anatomy I have to use the compound microscope, through which I can see this, under 100X magnification:

10-day-old bipinnaria larva of Pisaster ochraceus, 12 June 2015. © Allison J. Gong
Ventral view of 10-day-old bipinnaria larva of Pisaster ochraceus, 12 June 2015.
© Allison J. Gong

Aside from the dramatic increase in overall size (almost 1 mm long now!), the larva's body has gotten a lot more complicated. For one thing, the animal's marginal ciliated band, which propels the larva through the water, has started becoming more elongate and elaborate. In this view the larva is lying on its back, and I have focused on the plane of its ventral surface. The left and right coeloms are in the plane of the dorsal surface, and thus are not really in focus. You should still be able to see how long they have gotten, though. Eventually they will fuse anteriorly to form a single cavity. The stomach of the larva has a nice green-golden color due to the food it has been eating. It makes perfect sense, as we are feeding them a cocktail of green algae and a diatom-like golden alga.

The larvae are very flexible and can be quite animated when they're swimming around. They bend, scrunch up, and swallow food cells. They have already gotten so big that they take up much of the field of view under the microscope, even at the lowest magnification. Watch some larval gymnastics:


Part of the reason that I wanted to spawn Pisaster and raise the larvae this summer is that I want to put together a series of pen-and-ink drawings of the developmental stages. I did the same for the bat star Patiria miniata several years ago, but the Pisaster larvae will have longer and more elaborate arms when they mature; capturing these in drawings will be a challenge for me. I also hope to include the juveniles in this set of drawings. With that goal in mind, I've been sketching the larvae every few days, just to get some practice under my hand and remind myself what it feels like to draw. I've missed it!

10-day-old bipinnaria larva of Pisaster ochraceus, drawn from life. 12 June 2015. © Allison J. Gong
10-day-old bipinnaria larva of Pisaster ochraceus, drawn from life. 12 June 2015.
© Allison J. Gong

For whatever reason, I really like how this sketch turned out. It's not pretty, but it does truly represent what I saw under the microscope. I'm going to have to work on depicting three-dimensional structures on a two-dimensional page, which will take some practice. Fortunately I have several weeks to brush up on my skills!

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When I was in graduate school I found myself drawn to the "old-fashioned" skills of classical zoology:  observation of and experiments with living animals. I had, and still have, very little interest in the new-fangled high-tech methods of studying animals, and part of me strongly resents having to homogenize an animal to know what its name is. I leave that sort of biology to the systematists because, after all, the animal doesn't care what name we give it, and the names themselves are merely a way for us humans to communicate amongst ourselves (although in the best of all possible worlds the taxonomy reflects the evolutionary history of the group in question, which is itself a Very Useful Thing). I am much more interested in what the animal actually does as it goes about living its life.

A priest I know has said repeatedly that observation is a passive activity, and I've told him that he wouldn't think so if he actually knew how to do it properly. Careful observation takes a tremendous amount of mental focus, and like all other skills gets easier the more one does it. But I fervently disagree that observation is at all passive. If it is, then you're not doing it right. There are tricks of the trade that facilitate observation, of course, such as sketching and annotation, and I have all of my students do at least some drawing. My upper-division students keep a lab notebook that consists of drawings and notes that document their lab activities during the semester. Sometimes they grumble about having to draw and most of them worry about their self-perceived lack of artistic skill, but they do come around and realize that drawing forces them to really pay attention to what they observe. And no, I do not allow them to substitute photographs for drawings.

In graduate school I was fortunate enough to fall under the tutelage of one Todd Newberry, who directly and indirectly shaped how I think about animals and biology. He also taught me a specific type of scientific illustration, which he himself had learned from a pair of biologists in Paris. I used these techniques to draw the life history stages of my dissertation study organism, the moon jelly Aurelia sp. My favorite of this group of drawings is the juvenile medusa, or ephyra:

Pen-and-ink drawing of ephyra of Aurelia sp. Scale bar indicates 1 mm. © Allison J. Gong
Pen-and-ink drawing of ephyra of Aurelia sp., oral view. Scale bar indicates 1 mm.
© 2015 Allison J. Gong

Several years ago now, I put together a handout of sea star larval development for my invertebrate zoology students. These pen-and-ink drawings were done using the same techniques, but I left out the stippling as the larval anatomy became more complex. Part of the beauty of drawing as a means of documenting my observations is that I can select what to include which obviously reflects what I feel is important. Sometimes the decision about what to omit helps me focus on the structures that really matter, which of course depends on the purpose for any particular drawing.
Patiria development

 

So there are some of my drawings. One of my goals for the summer is to put together a suite of similar drawings of my sea urchin larvae, to complement the sea star set. It will give me an excuse to clean out my technical pens--they've been sadly neglected for years, and I hope they can be revived--and spend time with my photographs. I also have plans for some pencil drawings on black paper. I'm looking forward to tapping into the artistic side of my brain again for a while!

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