Origami Tarantula with Cordyceps

Crease Pattern

Design

I made this for April 2021 design contest in Origami-Dan. The theme was "same subject", which later was decided as "parasitoid fungi species affecting invertebrates".

Most likely the model to be made is insect, with weird fungi grow out of it. We'll need many skinny structures for the legs or fungi, meaning that there will be many sinks or pleats. I was tired of folding boxpleated models so I wasn't interested in participating. Nevertheless I saw some reference pictures and came across this tarantula with growths coming from its legs and head.

Source: http://www.upsocl.com/verde/cordyceps-el-extrano-parasito-que-transforma-insectos-en-zombies-crecen-ramas-en-todo-su-cuerpo/

That night I could't sleep and somehow cycled through possible structures for the infected spider. I got the idea of using a bird base, with the shortest flap as spider abdomen, one flap split to make fangs, two flaps as two of the legs, and one flap got color changed to become the fungi.

From this structure, I extended it to make the other legs and enlarge the fungi. It is straightforward to just keep adding bird bases (or in the case below, waterbomb bases) since spider legs don't need river and have uniform length. The fungi part can be extended using boxpleated style flap I used in leafcutter ant.

The fang parts are now middle flap. Splitting a middle will be pain but should be doable. There are empty spaces to be filled. I thought to just fatten the corner/edge flap legs to absorb the empty spaces, which will help to reduce the unsightly different leg thickness made from center, edge, and corner flaps. Then I got the idea, what if I used the extra layers to branch the legs, and color change the branch to make fungi growth coming out of the legs. It should work and I quickly jot down that idea.

The note that night.

Day after that I draw the overall structure in Orihime and do test fold with double tissue. The mountain/valley lines are obviously wrong but you got the idea. The fungi part is not boxpleated because I want it to be wide, fat, and fruity. It is just a shifted bird base to skew the flap's length. The idea of mixing boxpleating and traditional structures made me interested in finishing this design.

I had to use many of the 'Y' looking structure to support middle flap splitting on the fang/pedipalps area. 

Test fold using kami for the middle part, for spider's body.

The overall test fold.

Apart from the messy fold, the concept works. I completed the crease pattern as below.

The big fungi part has an inverted middle flap. What it means is this middle flap is like sunken and protruding from the underside of the model. It will have different color than the rest of the model which is perfect for the fungi. This was the first time I utilized it, and it was accidentally discovered during test fold.

The middle flap splitting to make head area bothered me a lot. Not only it introduced many layers and difficult to fold, it is also hard to shape well. Then I got the idea of using Lang's tarantula's body, which is just a bird base. From the four long flaps, two opposites flap become pedipalps, one become abdomen, and one got "Yoshizawa Split" to form the fangs.

I plucked that structure and paste it on this design. The structure changed a bit. Beside making the structure less cursed, it also yield better efficiency for the spider parts. The abdomen is 25% longer than before.

General idea on the packing. Smaller branching flaps circle/river are not shown. The four smaller and touching circles on lower left part shows Lang's tarantula's part that I used.

The final crease pattern is shown on top of this post. I actually draw the full mountain/valley assignment after folding the final model.

Fold

Based on test fold, the legs will be at the limit of the thickness that I am willing to work with. I could go with single tissue and just patch the borders for color change. That would make the legs having different color though due to some parts getting yellow paint bled while others don't. Finally I decided to just use double tissue.

Collapsing.

Finished base, just before shaping.

Lots and lots of patience to arrange and glue the layers, and then pleat the legs. I intended to make the legs curl to show that the spider is dead. However the thickness prevented me to do so.

I don't think I will come up with boxpleated design anytime soon. The final fold is shown on top of this post.