There is the other daddy-long-legs ( http://en.wikipedia.org/wiki/Opiliones ) I'm more familiar with. It's also known as a harvestman and is not a spider and has no venom whatsoever. Kangaroos do fart and other birds can see blue. Indeed, some bowerbirds specifically use blue objects to decorate their bowers.

I wouldn't put art on the list of uniquely human behaviors. Bowerbirds create some pretty amazing displays. And there's all the "performance" art of different species mating rituals. And before you try to make a distinction between human and animal art, think about how many teenage boys learned to play guitar or wrote poetry so they could impress the girls. Humans creating art is really just a sexual/social act. That it's developed into things as incredible as Bach's fugues is just a matter of degree.

Abstract mathematics, though, is definitely something uniquely human. I can't think of anything like it outside of human behavior.

I was impressed. If I were a Bowerbird I'd so move in.