Last year KIJK, a popular scientific magazine in the Netherlands,  asked me to make some cutaways of objects and animals. I could give my own suggestions and one of those was an octopus. Since I am not in the habit of just copying other peoples artwork and since I couldn’t find any appropriate photographic material on the internet on what I wanted to do, I drove to Urk, a small fishery town nearby.

I started at the auction and asked if they had octopuses and if they were complete. As it turned out, octopuses are bycatch and brought to the auction approximately once every two weeks. And they are always gutted. So I had to specifically order a complete octopus. I gave my name and number to the auction master and back home I started to look for fishing companies that advertised with octopuses on their site. One of them was able to help me. The first octopus, a few weeks later, was gutted so I had to wait for another. Finally, a month and a half after I ordered the octopus, two arrived in Urk from Italy.

Dissecting

The octopuses were packed in a Styrofoam box with an icepack on top of them. They didn’t smell all too pleasant, but as far as I could see they were fresh enough and complete. Having two dead octopuses in a box is a bit of a puzzle. You can’t see were one ends and the other starts. To detangle them I started with the largest body and took that out of the box on my kitchen sink.

Dissecting an octopus in my kitchen seems a bit gruesome but octopuses are considered food and my kitchen has very good lighting so I was able to see everything as good as possible.

I photographed every detail from the start. First the exterior, so I could make a believable octopus. What I noticed was that the arms are very long and to the end very thin. The syphon is a kind of floppy funnel in the middle of the octopus and hangs on ligaments. Even though the octopus was dead, the skin of its back displayed a beautiful pattern of different colored dots.

I opened it up and systematically identified all organs and structures. If you look up “octopus anatomy” on google images you will mainly find very schematic illustrations of the internal organs. They don’t do the anatomy of an octopus justice because what I saw was a piece of art. A tightly packed, clean bundle of clearly distinguishable parts with a great sense of symmetry.

Almost a pity to take apart. But I did. I photographed everything from different angles for reference of the 3d model I was planning to make of it. I knew that, at that time, I couldn’t model every little detail of the octopus. But because it is a pity to waste anything I tried to be as complete as possible. In the back of my mind I dreamed of a library of very detailed anatomical models. I still do.

I noticed that the only parts of an octopus that have some rigidity are the brains, the beak and buccal mass and a large gland in the body that functions as a liver. I opened the gland to see what’s inside but a rather homogenous mass came out. The parts of the beak felt like scales and the skull as thick cartilage.

The large octopus I started with turned out to be a male. I didn’t do the smaller one since the dissection took several hours and an octopus smell only stays  bearable for a limited amount of time.

Modeling

Because this was going to be an organic and very complex model I tried several applications. Poser has already an octopus in their default library. But that is a hideous thing, not fit for what I wanted. I didn’t choose Blender because at the time I was still learning that application and that would add even more hours to what I knew would be a painstaking process.

Finally I choose ZBrush. ZBrush is a digital clay program that is especially used for organic models. I work with it a lot and it is one of my favorite applications. Before I did the dissection I already made a model of an octopus with it but that one didn’t fit my purpose. And at the time I wasn’t able to change it in such a way that it would fit. Now I can and that is one of the great aspects of my work: my skills still grow exponentially each year. But that’s an whole other story which I am planning to write on this blog some time also.

Anyhow. The model of the octopus itself. I always like to add awe to my work. It would be printed on a spread in portrait orientation A3 size. So I had some space to work with. The octopus had to be up close and personal. So I imagined the spread as a window pane the octopus stuck onto from the other side. That way we could see its beak and suckers. The octopus itself, of course, would try to get to our side, so the arms of the octopus would come right at you, dripping with water. Because I wasn’t able to animate an animal at the time, the model had to be posed right from the start. I used a blank plane the size of the spread that the octopus would enfold.

ZBrush has several methods to start with. At the time I was most familiar to Zspheres, so I used those. I placed the Zspheres as good as possible, skinned it and started working on the model. That is basically sculpting, similar to real-life clay sculpting. The hardest part were the suckers. Because of the fact that I started with an already posed model, I did them one at a time instead of generating them in symmetry. That was a lot of work, something I now have a workaround for but a year ago it took me days to complete. With the rise of detail I went back and forth between ZBrush and Sculptris. At a certain point the model was too large, so I couldn’t work in Sculptris anymore.

After I was satisfied with the overall model, I textured it. I used mostly the photographs I took from the dissected octopus, but I made the model a lot darker than that one. ZBrush has the possibility to paint the model and use self-made textures.

The intestines

If I would do it all over again I would do it differently, but I started making the intestines after I finished the outer anatomy. And that gave me some problems. Although an octopus is very flexible, some parts are less flexible than others. The length of the esophagus for example doesn’t change much. So when I started incorporating the intestines in the outer anatomy model, that already was highly detailed and painted, some parts didn’t fit. Since the intestines were so beautiful, I had to change the outer anatomy, especially the position of where the beak should come out. If you look closely at the finished illustration you can see this adjustment.

Photoshop

I made the adjustments, rendered the model several times to get images of each part of the octopuses anatomy and went on to Photoshop. There I combined everything, using different layer styles to distinguish between one organ and another. I have a specific layer make-up in my library that I use for waterdroplets and I used that for the arms that came out of the water.

Total workload

This illustration took me more than a month to make. And then I mean only working with ZBrush, Sculptris and Photoshop. The process of getting the octopus had a turnaround of almost two months. Dissecting and photographing the octopus only took me 5 hours.
What would this illustration take me now? I think a lot less than a month, maybe even less than half that time. I now know how to animate models, have a better understanding of Dynamesh, a great tool within ZBrush that enables you to make better models, even if they are so complex, and I would use Blender as a finishing application instead of Photoshop.