Study

Exploration, play and habituation in octopuses (Octopus dofleini)

Mather, Jennifer A.; Anderson, Roland C.

Journal of Comparative Psychology, 1999

Peer-reviewedcontrolled laboratory experimentcaptive

What they did

Octopuses were repeatedly given inedible floating objects — pill bottles — and their handling recorded across sessions to distinguish initial exploration from later, changed forms of interaction.

Studied in: Enteroctopus dofleini
Sample size: 8 giant Pacific octopuses given floating objects repeatedly

Initial responses were exploratory and declined with familiarity. Two of eight animals then began repeatedly blowing the bottle across the tank into the water inlet current so that it returned to them, a pattern not explicable as exploration or feeding.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The behaviour meets the criteria for play: repeated, apparently purposeless interaction with a familiar object after exploration has ceased.

How NatureHQ reads it

Two animals out of eight, which is exactly how NatureHQ should report it. Octopus play is widely stated as fact on the strength of this study, and what it supports is that some individuals of one species did something that fits the definition of play. That is genuinely interesting and considerably narrower than "octopuses play". The distinction between exploration and play — has the animal habituated first? — is the part worth teaching.

Limitations

Two of eight individuals showed the behaviour; six did not.
One species, in captivity, with limited environmental enrichment otherwise.
"Play" is defined behaviourally, and the definition is contested for invertebrates.