Humboldt squid are noted for their extremely aggressive behavior during feeding frenzies but rarely do you see one attack something as an individual. In certain instances, however, they have attacked underwater cameras to the point that the cameras no longer operated properly.

According to Wikipedia they “…often approach prey quickly with all ten appendages extended forward in a cone-like shape. Upon reaching striking distance, they will open their eight swimming and grasping arms, and extend two long tentacles covered in sharp ‘teeth’, grabbing their prey and pulling it back towards a parrot-like beak, which can easily cause serious lacerations to human flesh. The whole process takes place in seconds.”

This attack behavior is definitely observed in this film short just off the coast of British Columbia (Google Map link):

(via TONMO)