A motionless European mantis (Mantis religiosa) waits to ambush a bee-mimicking fly. Then, seizing the fly with its forelegs, the mantis eats the mouthparts and eventually the face off the fly while it's still alive. The fly never stops writhing (presumably in pain), not even after its entire head is gone.

This footage, from YouTube user francischeefilms, is pretty gruesome on its own, but it's the audio that makes this meal especially ghastly.

[Via Gizmodo]