Amphibian

A bullfrog hops out from under a hedge, croaking loudly. A few feet away, another emerges and begins to sound off in turn. A third frog — this one evidently a female and the object of the attentions of the first two — peers out of the hedge, listening. Suddenly, the first male hobbles over to the second; they stare at each other for a moment, their croaking reaching a crescendo, then they begin to tussle ferociously. After a bit of grappling the first frog bites open the chest of the second and tears out his heart, which he then releases. The second frog desperately grabs for the heart and swallows it, but it's too late; after a second or two he collapses feebly and dies.

At least, that's the kind of dream you have after you've been to see Grizzly Man for a second time.