0ct0pus:

While they are not psychology majors, octopuses can be very clever when it comes to hunting strategies.

I especially love this one, a scare tactic quite efficient, especially with shrimps. The octopus will creep up to its prey and tap it on its shoulder. Out of sheer reflex, the startled victim will leap away from whatever touched it, ending into the clutches of the waiting octopus. 

Simple and effective. But in order to do that, the octopus must be able to understand some basic psychology, or to project itself in the mind of the victim. Or maybe I go too far, but in any case I find it amazing ! 

(the video comes from the University of California, Berkeley)