Painting Nudibranchs: Blue Glaucus

I took this past week off to rest and recuperate after the one-two combo of preparing for my Mid-Candidature Review and coming down with the flu in the middle of doing so, and I finally got around to painting again (which I hadn't done for about three weeks due to all that). I also started a new painting yesterday for the first time in a few months now, and then painted for four straight hours today to finish it as I just couldn't put it down once I'd started. I took a few pictures along the way, so you can see how it progressed.

When I first started painting last year, I only had plans for doing primarily inanimate targets: landscapes, astronomical vistas, things of that sort. I didn't feel very qualified to try painting something animal and alive. After painting a few small animals in various paintings which came out quite charmingly, however, about two months ago I began to want to try my hand at a larger animal painting. During this time I accidentally inspired myself as to my choice of target for my first foray into this new artistic territory when I was showing pictures to a friend of my favorite neustonic aeolid nudibranch: the blue glaucus, Glaucus atlanticus (also sometimes known as a sea swallow, or blue dragon). If you don't know what some of those words in the previous sentence mean, I'll explain as I go through the painting process.

I wanted a nice, sandy-looking background for this painting, so I started by making what looks like a piece of modern art. I decided to mix directly on the canvas, so I put some colors (skin tone base, titanium white, primary yellow, and Australian ghost gum [off-white]), gel containing natural sand, and some glazing medium to lower the overall viscosity of the mixture. I then mixed all this together with my painting knife, then smoothed it out (and covered the sides of the canvas) with a brush. I might talk about this in another post, but the joy of tactile manipulation of gels and mediums around the canvas is one of the big draws of painting for me.

Getting back to the painting subject, the blue glaucus is a nudibranch, or as they're more popularly known, a sea slug. Nudibranch means “naked gill,” as these slugs have external gills on their bodies. They're often brilliantly colored, and can be extraordinarily beautiful.

Nudibranchs come in two main divisions, the dorids, which look more-or-less like land slugs with a single feathery plume of gills on their back, and the aeolids, which have lots of soft horn-shaped cerata on their backs or sides. These cerata function as gills, but also as defense systems, as many aeolids feeds on cnidarians like jellyfish and sea anemones. The sea slug eats the stinging cells (or cnidocytes) from their cnidarian  prey without setting them off, and transfers them to specially-prepared pouches (called cnidosacs) in the tips of its cerata where it can use them to defend itself from predators. (This process of stealing cnidocytes is called, logically enough, “kleptocnidy,” a word which I can only guess the correct pronunciation of as I couldn't find it in a dictionary.)

Here's the finished sandy background, and here's where I tried something new: instead of free-hand painting, I sketched a blue glaucus out beforehand so I could correct the reference and get it right before putting paint down. The blue glaucus is unusual for a nudibranch, in that, unlike nearly all of its brethren, which live sensible benthic lives on the ocean floor, it spends its life floating on the surface of the ocean eating jellyfish. The correct term for this behavior, I learned today, is “neustonic” (and not pelagic as I previously thought, which properly means free-swimming creatures).

Here's a shot partway through the panting process, where I'd filled in all the lighter silver and silvery-blue parts. Interestingly, the blue glaucus floats upside-down on its back, so what we see from the top is actually is stomach (and foot, since it's a slug, though it doesn't really use it like other slugs do). It displays reverse countershading coloration, whereby it looks darker on top to be harder to see from above against the ocean, and lighter on the bottom to be harder to see from below. (In fact, its back is a nearly solid silver color.) From this position, floating on its back in the ocean, it lives off of jellyfish-like creatures (among them the Portuguese man o' war, the by-the-wind sailor, and the blue button) and even similarly-neustonic violet sea snails.

“Carefree Blue Dragon (Glaucus atlanticus)”, 30×40 cm, acrylic on canvas.

Anyway, here's the finished painting! Here you can see the blue glaucus in all its glory. While most aeolid nudibranchs have their cerata on their backs, the blue glaucus instead has them in bunches along its sides.

I'm pretty happy with how it turned out, but I'll probably touch this painting up a bit. I wanted to give the impression of viewing a blue glaucus floating in shallow water above a sandy bed, so I may add some minor features to the background (pebbles, small shells, maybe a shadow from the slug, etc.). Also, I think I made the cerata on the first pair of ‘wings’ a bit too short. Based on the pictures I looked at it seems like the span of that first pair of cerata is about as wide as the slug is long, but that seemed too extreme while I was sketching it so I shortened it a little. It looked fine in the drawing stage, but I'm now thinking I might need to go back and extend them out a bit longer. Luckily that shouldn't be too difficult (other than trying to match the colors I used before).

Other than that minor quibble, I'm quite happy with the coloration and general proportions (though looking at it now, the tail might be slightly too long as well). I spent a lot of time looking at pictures and drawing some sketches to try to get an idea of how the proportions worked (such as how the tips of the cerata in a ‘wing’ tend to extend out to the edges of an imaginary ellipse) and I think it shows through in the painting. Oh, I forgot to mention that these things are actually pretty small, only about an inch or two in length, so this is several times larger than life size!

It's definitely been fun to try painting something living, and I'll probably try it again in the future once I get some more inspiration. It also feels good to get back to painting after a forced absence from it. A hui hou!

Edit (29/09/2019): Well, in my usual fashion of picking up paintings again after I originally thought them finished, I've gone back and made some changes to this one. It turns out I made the first pair of cerata too short, so I lengthened them up a bit, though I liked the first version better aesthetically. (The lengths looked fine when I was sketching, but comparing the finished painting to photos I realized they definitely needed to be longer.) I also added a floating shadow, to give the illusion of looking down at a sea slug floating in a shallow pool. If I'd been thinking I'd have sketched in the shadow in the design phase and painted it first, but… Anyway, I think I'm happy with this version.