Actually, yukkuris do eat each other. Although normally that's when they don't know if it's another yukkuri (of if they're a shithead), and there's none specifically of yuyukos yet. However, given their seemingly huge appetite it's quite possible they'll be driven to eat each other easier...
And after all that, the Yuyukos weren't tagged in the picture... some of them seem to have bodies, so they might either be bodied yukkuris, just clones of the character, or a mix of both.