@ScrewedUpDollie & @yo: I agree totally. Stop using unfounded, illogical arguments, guys! That's what the fundies do! You're not even right - bestiality is natural; get any two animals with a sex drive confined together long enough and, if they don't kill each other, they'll fuck. It has been observed a few times in closely related species, such as lion/tiger and horse/donkey. They even have names for the sterile offspring!
I have no objection to bestiality per se; my objection, as with others, is that it is rape. If a super-intelligent ape* developed enough language ability to give informed consent, and selected a human partner, and they were both up for it, that'd be fine. I'd personally find it a bit gross, but I'd get over it because there's no rational objection to it. I mean, Shatner fucked other species all the time on Star Trek!
Raping an animal that can't give consent is about equal to raping someone with a severe mental handicap: beyond disgusting. Horrible.
There is at least one example of a dolphin and a human cohabiting; it was initially an experiment in interspecies communication, but they fell in love. I do not know if the relationship was consummated (I hope not - this was a female human and a male dolphin. Dolphin penises are way big! Ow!), but if they're in love, is there really a decent moral objection?
BTW, I do (did) know someone who raped an animal, so I have discussed this already. No one talks to him any more...
*I mean a non-human, obviously; a bonobo or chimp or something.