Study
Spectral discrimination in color blind animals via chromatic aberration and pupil shape
Stubbs, Alexander L.; Stubbs, Christopher W.
Proceedings of the National Academy of Sciences, 2016
An optical model asked whether a cephalopod eye could extract colour information despite having only one visual pigment, by exploiting the fact that different wavelengths focus at different depths and that the unusual pupil shape exaggerates that effect.
- Studied in
- Octopus, Sepia, Loligo
The model showed that by changing focus and using an off-axis, U-shaped pupil, an animal with a single photoreceptor type could in principle infer wavelength.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Chromatic aberration combined with pupil shape offers a plausible route to colour vision in otherwise colour-blind cephalopods.
How NatureHQ reads it
A proposed solution to a real puzzle: cephalopods produce astonishing colour displays and match their backgrounds, yet their retinas contain a single visual pigment. This is a model, not an observation — no experiment has yet shown an octopus using this mechanism, and other explanations, including light sensitivity in the skin, are live. It belongs in the "promising idea" column rather than the "how it works" column.
- Purely theoretical; no behavioural or physiological test.
- Requires slow focus adjustments that may not fit fast behavioural colour matching.
- Competing explanations remain untested against it.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Octopuses
Nobody has established how a colour-blind octopus matches coloured backgrounds
Octopuses
Octopuses do not copy their background — they pick from a few pattern strategies
Spiders
A jumping spider keeps its eyes still and moves the retina behind them, scanning like a scanner
Cuttlefish
Cuttlefish produce convincing colour matches and, by the standard measurement, cannot see colour — their camouflage response tracks brightness and ignores hue. Nobody has settled how they manage it.
Published by: Proceedings of the National Academy of SciencesPublished in PNAS.
doi.org/10.1073/pnas.1524578113
Checked against Crossref and OpenAlex on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-09.