A pygmy octopus with a mantle of barely 33 mm (1.3 in), dark gray to purple with cream to lilac spots in a mosaic pattern. It lives in very shallow water, from the shoreline down to about 5 m (16 ft), on rubble and among coral fragments, and it is small enough that most divers who pass one will register a moving stone.
The second common name, drop-arm octopus, is the useful one. Members of this genus shed an arm when something grabs one, and the detached arm keeps writhing on the bottom for minutes: the nervous system of an octopus arm is largely local, and it can run its own movements without the brain. The predator stays with the moving piece while the animal leaves. The arm regrows.
Males court with posture and color and mate at arm's length, passing a sperm packet along a modified third arm. This is one of the few octopus genera where males have been recorded fighting and guarding females rather than mating opportunistically.
Everything else about it is unrecorded. It was described only in 1997, from Philippine material, and there is no published account of its diet, lifespan or breeding in the wild. The gaps here are real, not an omission.
- mosaic of dark gray to purple with cream and lilac spots
- very small, mantle barely 33 mm
- shallow rubble and coral fragments, often under 5 m
- may leave a shed arm writhing behind it
Why it's threatened
Because this species lives on coral reefs, it may be threatened by ocean acidification and global warming of seas, as these phenomena are likely to lead to habitat losses in the future.
Threat classification from the IUCN Red List.
