Although all octopuses can change colour and texture, and many can blend with the sea floor, appearing as rocks, the mimic octopus is the first octopus species ever observed to impersonate other animals.
Based on observation, the mimic octopus may decide which animal to impersonate depending on local predators. For example, when the octopus was being attacked by damselfish, it was observed that the octopus appeared as a banded sea snake, a damselfish predator. The octopus impersonates the snake by turning black and yellow, burying six of its arms, and waving its other two arms in opposite directions.
The mimic octopus is often confused with Wunderpus photogenicus, another recently discovered species. The Wunderpus can be distinguished by the pattern of strong, fixed white markings on its body.
Be sure to watch about a minute eighteen in when the mimic turns into a cute fuzzy something running on two legs. Yeah, I don’t know how to describe it, but that is one of the more fascinating characteristics of the octopus, when it turns into things we can’t figure out.
(via marginal revolution)