octopus

A robotic vehicle was exploring the ocean floor by Hawaii, more than 2 1/2 miles underwater. To the surprise of NOAA scientists, it came across a cute, "ghostlike" octopod. One suggested name: Casper.

When the gloomy octopus of Australia turns dark and towers threateningly over his neighbor, he's likely signaling aggression, scientists now say. Neighbors get the message — they turn pale and flee.