Two honest categories live on this page. Vision means photoreception: a pigment molecule absorbs a photon and the eye builds a picture, in whatever band evolution tuned it to. Radiant heat means the organ absorbs infrared radiation and feels the microscopic warming or mechanical change it causes. That is real electromagnetic detection, but not color seen the way an eye sees red or violet. For the heat-sensers, the highlighted band below is the radiation their target emits: a warm body, a wildfire, an ankle.
The strip on top is the close-up, far infrared to near ultraviolet, where every creature on this page lives. It funnels down to the bar underneath, which is the whole spectrum from radio to gamma, and the gold window there is the sliver the close-up covers. Polarization is a second property of light rather than a wider band, so it gets its own wing below.
Static and slowly changing electric or magnetic fields are electromagnetic, certainly, but they are not propagating light, so they have no place on a wavelength ruler. Assigning a shark a wavelength range would be physics wearing a counterfeit mustache. These senses get their own wing:
Ampullae of Lorenzini read the faint electric fields leaking from every living body: nerve and muscle activity betrayed through seawater. Weakly electric fish go further: they emit their own field and read how nearby objects distort it, an electric flashlight for the dark.
The bill is packed with electroreceptors. Hunting with eyes, ears and nostrils closed, a platypus finds prey underwater by the electric fields of their muscle twitches, cross-referenced with touch to judge distance.
Songbirds crossing continents read Earth's magnetic field for compass direction, and likely parts of their map. The leading suspect is a quantum effect: magnetically sensitive radical pairs in cryptochrome proteins of the eye, which would make the compass something a bird sees.
Light is a wave in the electric field, and that field swings across the direction of travel: up-and-down, side-to-side, or any angle between. That angle is polarization, and nothing in a human eye registers it. The sky is full of it all the same. Air scatters sunlight most strongly at right angles to the sun (the same 1/λ⁴ scattering that makes it blue), and light scattered through a right angle comes out almost fully polarized, so a great ring of polarized sky runs 90° from the sun all day. Some eyes read that ring as a compass; some read polarization the way yours reads colour.
Colour-blind, and yet it sees a channel you cannot: cuttlefish tell polarization angles apart to about 1°, the finest polarization vision measured in any animal. Transparent prey that vanish in plain light stand out in polarization contrast, and the skin can flash polarized patterns invisible to most of the reef.
Rolls its ball in a dead-straight line away from the pile by reading the polarization pattern of the sky through a special strip along the top of each eye. The first animal shown to steer by polarized moonlight, a million times fainter than the day sky; on moonless nights it switches to the glow of the Milky Way.
Reads linear polarization like the cuttlefish, and then goes one further: the only animal known to detect circular polarization, light whose field corkscrews as it travels. It uses the channel for private signalling, and its eye has been copied into camera filters.
Karl von Frisch found in 1949 that bees steer by the sky's polarization when the sun is hidden; a patch of blue sky is enough. Desert ants of the genus Cataglyphis run the same compass to walk hundreds of metres out over featureless sand and straight back to a centimetre-wide nest hole.
Laboratory experiments have found acute responses to X-rays in several animals: most strikingly, C. elegans worms perform an immediate avoidance maneuver, mediated by LITE-1, a receptor protein otherwise tuned to ultraviolet. That is real, and it is not a naturally evolved, image-forming X-ray eye. File under experimental edge case, radiation-warning halo attached.
All ranges are approximate and drawn from behavioral and electrophysiological studies; species vary, and the near-infrared fish work in particular reports behavioral response bands, not full visual sensitivity curves. The compact version of this page lives as the Senses layer of the Observatory.