I'd have to agree with ReturnToOne. Those pics are illustrations and don't really try to show up the horrific qualities of any of the creatures. Horror is a bit easier to build up when people are guessing at the details. Implying things and letting the audience fill in the details is how people get hooked on horror stories to begin with. The extra thinking you do about what's really there gets you invested in the story. I'd probably wait and show the pics after a group encountered one, killed it, and had a chance to look at it in the light. Afterwards though, I agree they'd add to that "disturbingly unnatural monster" feel.