Study

Self-recognition mechanism between skin and suckers prevents octopus arms from interfering with each other

Nesher, Nir; Levy, Guy; Grasso, Frank W.; Hochner, Binyamin

Current Biology, 2014

Peer-reviewedphysiological studylaboratory

What they did

Octopus suckers were offered various surfaces, including octopus skin, skin extracts and inert objects, and their grasping response was measured. Live animals were also given amputated arms — their own and those of other octopuses — to see what they would grip.

Studied in: Octopus vulgaris
Sample size: amputated arm preparations and behavioural tests

What they found

Suckers reflexively grip almost anything but do not grip octopus skin. Live octopuses handled another octopus’s severed arm readily, and handled their own with noticeably more caution.

What it means

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

How the authors put it

A chemical signal in octopus skin suppresses the sucker grasp reflex, preventing the arms from seizing one another.

How NatureHQ reads it

A beautifully economical answer to a problem eight flexible arms create: rather than a brain that tracks where every limb is, the solution is a chemical rule at the skin — "do not grab this". It is a good illustration of how an intelligence built on a different plan solves a problem vertebrates solve centrally. The observation that an octopus treats its own severed arm differently from another’s is intriguing and rests on a small number of trials.

Limitations

Much of the evidence comes from amputated arm preparations rather than intact behaviour.
The self versus non-self arm discrimination rests on few observations.
The chemical signal was characterised functionally, not fully identified.