It's a tough question: Are humans morally superior to other animals? My instincts say yes, but the arguments siting the exclusivity of "sentience" or "rational thinking" seem thin to me, especially in light of what we've been learning about animal behavior in the last couple of decades. (See Frans de Waal's
Are We Smart Enough to Know How Smart Animals Are, or John Gray's wonderful meditation on human-animal relations,
Feline Philosophy: Cats and the Meaning of Life.)
More visceral is the footage of a blue whale in the opening sequence to David Attenborough's documentary,
Blue Planet: Seas of Life. The photography team found one and used an ultralight aircraft to drop a diver in front of it (boats can't keep up because blue whales cruise too fast). As the largest animal that ever existed moves toward and past the diver, Attenborough narrates some facts -- heart as large as an elephant, blood vessels a person can swim through, and so on. The moment is sublime. And I'm thinking, "So I'm a superior being? Hmm, huh, who the heck am I kidding?"
Despite not thinking myself morally superior to animals, I still eat meat and I've done a fair amount of hunting, including killing deer. We're killers. As
@AlpinLuke alludes, we kill without knowing it. Farming, of course, probably kills more animals than just about anything else due to habitat loss and pest control, so few vegetarians' hands would be blood free.
I always loved this passage from Aldo Leopold's,
Sand County Almanac:
There are two spiritual dangers in not owning a farm. One is the danger of supposing breakfast comes from the grocery, and the other that heat comes from the furnace.