Giant Pacific Octopus
"Oh my hat!" said the presenter upon seeing the Giant Octopus. Oh my hat indeed!
This giant beautiful creature can live for up to 5 years, and has been know to attack sharks. The largest recorded size was 272kg with a 9m arm span, though they usually grow to about 45kg.
They are very intelligent, being able to undo sealed containers and suchlike, and can learn by observation, a trait unknown in other invertebrates. They are also extremely inquisitive: In the video you can see how the octopus investigates the diver.
Apparently, their turquoise blood is not a good oxygen carrier, hence their need to live in the cold, deep, oxygen-rich waters. They even have no less than three hearts to help pump their blood around their bodies.
For more info, try:
National Parks Conservation Association
Giant Octopus Fact Sheet
Image: Jeff Rotman/Stone/Getty Images