How they see
How does a shark see the world?
Colour-blind, contrast-obsessed hunter
For all their menace, most sharks studied appear to be completely colour-blind, reading the ocean in brightness and contrast alone. A single cone type tuned to blue-green — the colour that travels furthest through seawater — does the daytime work, backed by a light-boosting mirror for the deep. To a shark, a swimmer is a moving silhouette rather than a palette of colours.
See through their eyes
Human ≈ 60 cpd (20/10)
How sharp is a shark's vision?
Its eyes resolve about 4 cycles per degree (20/150), while a human reaches around 60 cpd (20/10). Its field of view spans about 340°.
How does a shark see a human?
Its eyes resolve about 4 cycles per degree against your 60, so a face has to be roughly 15 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 shark see?
Little or no colour vision; relies on brightness, contrast and motion. Green-blue is where the ocean transmits light best.
Photoreceptors
Cone monochromat (single cone type) + rods
Cone peak sensitivities
- Single cone532 nm
How does a shark see in the dark?
Strong tapetum lucidum for deep, dim water.
How does a shark's vision compare to a human's?
A shark's roughly 20/150 detail trails your 20/20, and where you see millions of hues it sees none. A strong reflective layer behind its retina lets it hunt in dim, deep water where you would be blind.
What is special about a shark's vision?
- Effectively colour-blind
- Excellent contrast & motion detection
- Electro- and mechano-reception complement vision
What the research shows
The case for colour-blindness rests on microspectrophotometry, which measures how single photoreceptors absorb light. Hart, Lisney & Collin (2011) found only one cone pigment across the sharks they examined, with peaks between about 532 and 561 nm depending on species, alongside rods peaking between roughly 484 and 518 nm; the page displays the 532 nm end of that range. With a single cone type there is no second signal to compare, so hue cannot be computed from the retina's output. Other figures are much softer. Acuity estimates run from about 4 to 11 cpd across sharks and depend on species and method, and the simulation takes the low end, 4 cpd. Flicker-fusion values of about 18–36 Hz have been estimated for some sharks, but they remain estimates rather than a measured value for any one species on this page.
Two features complicate any picture of shark sight. The tapetum lucidum behind the retina can be masked by pigment, so its light-boosting effect is not fixed, and a constant brightness gain can only hint at it. More fundamentally, sharks also sense electric fields through the ampullae of Lorenzini and water movement through the lateral line, senses that complement vision but have no visual form. A blue-green grayscale frame conveys what a single cone would report; it cannot convey the electrical and pressure information arriving alongside it.
Guides: Are animals colour blind? · Which animal has the best eyesight? · All guides
Scientific sources
- Hart, Theiss, Harahush & Collin (2011)
- Gruber & Cohen (1985)
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