Monday, 21 October 2019

The prigoon: a secondary bilateral spidrid

I cannot imagine that anyone will remember that I wrote about animals that walk on five legs in this blog. Actually, I hardly did, and that is not surprising as it was almost exactly 10 years ago. Well, I did remember that I wrote about 'odd walkers', but had forgotten that I had actually produced an animation for an animal with two pairs of legs and an unpaired one.

So why bring this up? Because I am working on a painting of a 'secondary lateralised spidrid'. It's a small exoskeletal predator. Think of a jumping spider on Earth. The animal is descended from radially symmetrical spidrids, and during its evolution the new plane of symmetry somehow came to run through two opposite pairs, rather than between them. Mind you, these exist too, but for unknown reasons the latter group is almost exclusively herbivorous, while the ones with one jumping leg are mostly predators.

Click to enlarge; copyright Gert van Dijk
So here is a colour sketch. I think I will call it a 'prigoon', but I haven't thought of its binomen yet. The name will probably contain 'dougalii'  or 'dixoni', as Dougal Dixon was the first to come up with this odd arrangement, and I wouldn't want people to think I am quoting anything without a proper reference.