Shallow-water octopus that raises its skin into weed-like flaps and walks on two arms.
A small octopus with a mantle of about 7 cm and arms several times that length, common on shallow rubble, seagrass and reef flat across the western Pacific. Its usual resting appearance is the origin of the name: the skin is drawn up into numerous branched papillae and the arms held in loose coils, so the animal reads as a clump of algae on a rock. Colour shifts between mottled brown, green and white within a second or two. It is separated from the small Octopus species on the same ground by the very long, slender arms and by the mantle papillae.
Well studied for its behaviour. Individuals move across open ground in a bipedal walk, using the two rearmost arms while the remaining six are held gathered against the body in an algal shape, and males guard females and mate from a distance, extending a single arm to the female rather than approaching. Active by day, which is unusual for the group and makes it one of the easier octopuses to watch. Recorded from the intertidal down to about 15 m; on a muck site it belongs to the shallow section, and it is most often found in the last few minutes of a dive rather than at the bottom of one.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
