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THUBAN · KNOWLEDGE LIBRARY / EXPLAINER
More kinds of photoreceptors do not automatically mean better colour vision. The mantis shrimp shows why evolution is rarely that simple.
A remarkable visual system
Some mantis shrimp have twelve classes of colour photoreceptors, as well as other specializations including sensitivity to polarization. This compares with the three cone classes involved in typical human colour vision. It is tempting to conclude that these crustaceans experience a vastly richer rainbow, but that inference is not established.
The surprising experimental result
Behavioural research published in Science investigated wavelength discrimination and found that mantis shrimp in the tested conditions performed poorly compared with expectations for a conventional opponent-colour system. The authors proposed that their eyes might recognize colour categories quickly rather than make fine distinctions between similar wavelengths.
Eyes built for an ecological problem
Different mantis shrimp live at different depths and in light environments with different spectral characteristics. Studies of spectral tuning show that their visual systems can reflect habitat conditions. Seeing is not one universal challenge: spotting movement, communicating with partners and detecting polarized signals place different demands on an animal.
What this does not tell us
We cannot directly access the subjective visual experience of another species simply by counting receptors. The information its nervous system extracts and how it behaves matter at least as much. Nor should one experimental finding be generalized without care across every species of mantis shrimp.
The larger insight
Evolution does not maximize a single measure such as the number of colour channels. It generates combinations of mechanisms under ecological constraints. Strange biology becomes more illuminating when we ask what an adaptation does rather than only how impressive it sounds.
Sources and further reading
- Study — A different form of color vision in mantis shrimp (PubMed)
- Research — Spectral tuning and visual ecology
Editorial review: 10 October 2026 · Evidence, interpretation and uncertainty are distinguished throughout.