Zoo madness

In a couple of today's papers there is a story about how the hippos at the Basel Zoo killed one of the zebras (they're like the Crips and Bloods of the animal world, those two). I tried to do a translation of the story, and if I understand correctly, they were actually such good friends that the zebra would often eat out of the hippo's mouth (there's an appealing thought), but this time the zebra accidentally bit the hippo's lip, and when the hippo reacted, the other hippos jumped the poor zebra. There's probably a metaphor or an allegory in there somewhere--"Don't bite the lip of the hippo that feeds you", or something like that.