Incredible Invisible Octopus
By now most of you have seen this video, but I though I'd put it on here anyway for posterity.
This clip captures the incredible camflauge ability of the octopus.
If the comments on Digg are to be believed (and I have no question as to the absolute accuracy of digg postings), this octopus is an Indonesian Mimic Octopus (Thaumoctopus mimicus)
From its wikipedia article, this species of octopus will average about 2 feet in length and its natural colors are brown with white spots. The mimic octopus has the ability to not only camoflauge itself, but to mimic the movements of other underwater creatures such as sea snakes, flounder, lionfish, and flatfish.
There are a few more mimic octopus videos to be found at this site:
http://pharyngula.org/index/weblog/comments/indo_malayan_mimic_octopus/
And more info and photos can be found from this National Geographic article:
http://news.nationalgeographic.com/news/2001/09/0920_octopusmimic.html
