How they see
How does a sea turtle see the world?
UV-to-red colour beneath the waves
A sea turtle carries colourful eyes into a blue-green world, seeing from ultraviolet all the way to red through cones fitted with tiny coloured oil-droplet filters. Tuned to the light of the coast and the moonlit sea, its vision guides it across whole oceans. That same sensitivity, sadly, is why the wrong lights on a beach can send its hatchlings astray.
See through their eyes
Human ≈ 60 cpd (20/10)
How sharp is a sea turtle's vision?
Its eyes resolve about 6 cycles per degree (20/100 (est.)), while a human reaches around 60 cpd (20/10). Its field of view spans about 200°.
How does a sea turtle see a human?
Its eyes resolve about 6 cycles per degree against your 60, so a face has to be roughly 10 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 sea turtle see?
Broad colour from UV to red; sensitive to the wavelengths of coastal and moonlit light.
Photoreceptors
Tetrachromat with coloured oil droplets, UV-capable
Cone peak sensitivities
- UV/violet400 nm
- S (blue)450 nm
- M (green)502 nm
- L (red)570 nm
How does a sea turtle see in the dark?
Good in the blue-green of open water.
How does a sea turtle's vision compare to a human's?
A sea turtle's detail is around 20/100 to your 20/20, but it sees ultraviolet you cannot and is finely tuned to the blue-green light of open water, where much of your colour vision would drain away.
What is special about a sea turtle's vision?
- Sees ultraviolet
- Oil-droplet colour filters
- Drawn to specific light wavelengths
What the research shows
Sea-turtle colour vision was assembled from two kinds of evidence. Liebman & Granda (1971) used microspectrophotometry on green turtle retinas and found visual pigments near 440, 502 and 562 nm, each associated with a differently coloured oil droplet: clear, yellow and orange. Decades later, Levenson et al. (2004) measured photopic spectral sensitivity in green and loggerhead turtles and found that the two species do not match. Green turtles responded down to 400 nm, and their ocular media transmit light to about 325 nm, which points to ultraviolet capability; loggerheads showed no response below about 440 nm. Both species peaked in the long-wave region, around 580 nm.
So 'sea turtle' is not one visual system. The page's four values (400, 450, 502 and 570 nm) combine these sources into a representative set rather than reporting a single measurement, and its short-wave end describes the green turtle, not the loggerhead. Spatial acuity has not been established by a behavioural test; the notes estimate 5 to 8 cycles per degree, and the simulation uses 6 cpd. A screen cannot show what oil droplets do inside each cone, sharpening its spectral sensitivity, and ultraviolet has no equivalent among a display's three primaries.
Guides: Which animal has the best eyesight? · All guides
Scientific sources
- Granda & Dvorak (1977)
- Mäthger, Litherland & Fritsches (2007)
Download Animal Vision
Point your camera at anything and watch the world transform into this animal’s vision in real time.
