How they see
How does a common carp see the world?
Four cone channels from ultraviolet to red, with measured retinal detail
The common carp is a tetrachromat with ultraviolet, blue, green and red cone channels. Direct cell measurements found peaks at 377.5, 458, 532 and 600 nanometres, while adult retinal anatomy gives an estimated 3.60 cycles per degree of resolving power.
See through their eyes
Human ≈ 60 cpd (20/10)
How sharp is a common carp's vision?
Adult retinal anatomy gives an estimated upper resolving power of 3.60 cycles per degree, not a behavioural threshold. A species-level total field, binocular overlap and critical flicker value were not established, so no number is assigned to them.
How does a common carp see a human?
Its eyes resolve about 3.6 cycles per degree against your 60, so a face has to be roughly 17 times closer for it to pick out the detail you do. Your outline and your movement read clearly; your expression does not.
Colour comparison
How each colour shifts when seen through this animal's eyes, using the same colour model as the app. Tones a screen can't emit (such as ultraviolet) are shown as an approximation.
What colours can a common carp see?
Microspectrophotometry measured four cone classes, and conditioning in the same group of fish found a behavioural ultraviolet sensitivity peak near 380 nm under a long-pass background.
Photoreceptors
Tetrachromat with ultraviolet-, blue-, green- and red-sensitive cones plus rods
Cone peak sensitivities
- UV377.5 nm
- S (blue)458 nm
- M (green)532 nm
- L (red)600 nm
How does a common carp see in the dark?
Rods and retinal dark adaptation are present, but the cited studies did not establish a behavioural night-vision threshold.
How does a common carp's vision compare to a human's?
Humans normally use three cone classes and our lenses block ultraviolet; common carp use four cone channels extending into ultraviolet. An RGB screen can show only visible false colour and reduced detail, never the extra channel itself.
What is special about a common carp's vision?
- Four cone classes spanning ultraviolet to red
- Behavioural ultraviolet action spectrum measured in three conditioned carp
- Adult anatomical resolving power estimated at 3.60 cycles/degree; field and CFF remain unquantified
What the research shows
Hawryshyn & Harosi (1991) did more than find an ultraviolet cone; they showed how its contribution depends on viewing conditions. Using heart-rate conditioning in three carp, they found a small ultraviolet sensitivity maximum near 380 nm against a 450 nm long-pass background, and changing the adapting background made the ultraviolet mechanism more prominent and shifted the fitted maximum toward 400 nm. Microspectrophotometry on ultraviolet cones from one fish of that group gave 377.5 ± 4.5 nm, based on just five cells, alongside blue, green and red classes near 458, 532 and 600 nm.
An independent method gives somewhat different numbers. Kaneko & Tachibana (1985) recorded single carp cones intracellularly and found visible-light maxima near 460, 520 and 620 nm, a spread that reflects preparation and method rather than a contradiction. For detail, Zaunreiter, Junger & Kotrschal (1991) quantified photoreceptors, ganglion cells, convergence and eye geometry in adult carp, arriving at 3.60 cycles per degree; that is an anatomical estimate, and body size and retinal region can change it. No species-level field of view, binocular overlap or flicker threshold was found, so none is borrowed from goldfish or other relatives. On a screen, ultraviolet can only be marked with false colour, never shown as it is.
Guides: Animals that see ultraviolet · Which animal has the best eyesight? · All guides
Scientific sources
- Hawryshyn & Harosi (1991), Vision Res 31:567–576, doi:10.1016/0042-6989(91)90107-G
- Kaneko & Tachibana (1985), Jpn J Physiol 35:355–365, doi:10.2170/jjphysiol.35.355
- Zaunreiter, Junger & Kotrschal (1991), Vision Res 31:383–394, doi:10.1016/0042-6989(91)90091-I
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