A major threat to the world's porpoises comes from an unexpected quarter: Dolphins who aren't getting any.
Dolphins sometimes kick the crap out of porpoises just for funsies — they don't really compete for food, and science has not yet established the existence of dolphin racists, so it wasn't clear that there was any rhyme or reason to the vicious watermammal-on-watermammal attacks. But now it turns out that the aggro dolphins are mostly young males, so conservation expert Mark Cotter theorizes that this is basically aquatic Fight Club.
Get ready for some science talk: Young male dolphins don't have thumbs. So when they're sexually frustrated, they can't just play Mass Effect and/or jerk off like normal people. (Though they do have prehensile penises, so you'd think they could figure SOMETHING out.) Instead, they curb-stomp porpoises. Cotter describes this as "object-oriented play," which suggests he is suffering from Sea Fever, because the attacks actually sound pretty Clockwork Orangey:
In one particularly violent attack, three dolphins corralled their victim before seven others joined them to ram the porpoise to death. Cotter found most shocking the fact that two dolphins remained behind to play with the carcass before pushing it towards his boat.
Wooo, corpse soccer! If that's a dolphin's idea of play, then dolphins are assholes.
(h/t Brad Plumer for the title)