Mantis Shrimp Vision

Mantis shrimps, also called stomatopods, are marine crustaceans with compound eyes divided into upper and lower regions by a central band of ommatidia called the midband. The detailed arrangements vary among species. A peer-reviewed review describes up to 16 functional classes of retinal photoreceptors in species with a six-row midband, supporting different visual functions, including colour, ultraviolet and polarization sensitivity. Filtering pigments and the layered organization of some receptors help tune sensitivity across wavelengths; the number of receptor classes alone does not establish how well an animal discriminates colours.

Studies describe stomatopod vision as extending across visible and ultraviolet wavelengths, and report sensitivity to both linear and circular polarization in some species. In experiments with Gonodactylus smithii and Odontodactylus scyllarus, researchers observed torsional eye rotations that aligned photoreceptors with linearly polarized light, enhancing polarization contrast between a target and its background. This active polarization vision is a specialized capability, not evidence that every stomatopod species sees the same way.

A behavioral study of Neogonodactylus oerstedii tested recognition of red and green targets with different shapes. In conflicting-cue trials, animals tended to choose the trained shape rather than the trained colour; the difference was marginal and did not meet the conventional 0.05 significance threshold (P = 0.054). The authors emphasize that this result concerns their particular task and does not negate evidence that mantis shrimps can learn colour cues under other conditions. Such findings caution against assuming that an elaborate eye performs uniformly across all visual tasks.