Truth & Verification: The Mantis Shrimp's Twelve Color Receptors — and Why It Still Can't Tell Two Colors Apart

Everyone has heard the mantis shrimp fact: it has twelve types of color receptors in its eyes, compared to the three in yours. The pop-science conclusion is that the shrimp lives in a rainbow of colors humans can't imagine. A 2014 study published in Science found something stranger: the shrimp is actually worse than humans at telling similar colors apart.

The claim comes from a behavioral experiment, not a count of receptors. Researchers H.H. Thoen, M.J. How, T.-H. Chiou, and J. Marshall trained mantis shrimp to associate a food reward with a specific wavelength of light. Then they tested whether the shrimp could distinguish that wavelength from another one close to it on the spectrum.

Humans pass this test easily. We can tell the difference between two wavelengths only a few nanometers apart — that's why we see thousands of distinct colors. The mantis shrimp, despite its twelve photoreceptor types, failed. The shrimp couldn't distinguish wavelengths that look obviously different to a human eye.

This inverts the myth. More channels doesn't mean richer color perception. The paper suggests the shrimp's visual system is built for speed, not fine discrimination — it does rapid, coarse categorization of the world rather than the detailed spectral analysis humans do. In murky water where light is scarce and predators move fast, a quick approximate read may beat a slow precise one.

What remains open: the paper tested one species of mantis shrimp in a laboratory setting, and the researchers themselves noted that their behavioral test might not capture everything the shrimp's visual system does. Whether the shrimp experiences color as a "dimension" in the human sense is still unanswerable. But the headline claim is solid: twelve photoreceptors, worse fine color discrimination than a human, verified by experiment.