Octopuses

Some interesting facts about octopuses. First, that the plural "octopuses" is more correct than "octopi". That's because "octopus" isn't a Latin word, it's derived from a Greek one. If you want a fancy plural, you could say "octopodes".

Some interesting footage of octopuses and cuttlefish at the following site:

http://www.cephbase.utmb.edu/
Various bits of footage of different cephalopods.

http://www.oceanfootage.com/stockfootage
This is a site selling stock footage of ocean creatures, but you can watch the images in a smaller size for free. Search for the "mimic octopus".