How well can bats actually see?
"Blind as a bat" is biologically backwards. Not one of the world's ~1,400 bat species is blind, and some flying foxes out-see you in moonlight while certain insect bats perceive ultraviolet light your eyes cannot.
9 established, 2 disputed, 1 debunked, 1 unresolved. We do not pick an answer; the evidence places each claim. How we decide
47 citations from 19 independent sources - 28 echo the same voices and count once. Graded B1-D1.
Added 3 Jul 2026 - updated 6 Aug 2026
What the four states mean
- Establishedsupported, uncontested
- Disputedcredible sources disagree
- Debunkedrefuted by the evidence
- Unresolvedno settled answer
Established 9supported, uncontested
Some bats see better than humans in the dark — flying-fox retinas pack vastly more rod cells.▰▰▰▱▱ likely4 points
Supports- Some bats see better than humans in the dark — flying-fox retinas pack vastly more rod cells.Blind as a Bat? No Such Thing — Bat Conservation International analysis
- BCI: bats pack roughly 300,000–800,000 rods per mm² in their retinas, versus about 150,000 per mm² in humans, and large-eyed species like the Indian flying fox out-see us in dim light.Blind as a Bat? No Such Thing — Bat Conservation International analysis
- Flying foxes have far more rods than people and so navigate by landmarks, roads and streetlights with far better low-light vision than we have.The truth about flying fox vision — Sunshine Coast Council analysis
- At high brightness megabat visual acuity is poorer than humans', but at low brightness it is superior.Megabat — Wikipedia (citing primary sources) summary
Many bats see ultraviolet light — a band of the spectrum humans cannot perceive at all.▰▰▰▱▱ likely4 points
Supports- Many bats see ultraviolet light — a band of the spectrum humans cannot perceive at all.Bat Eyes Have Ultraviolet-Sensitive Cone Photoreceptors — PLOS ONE (PMC2712075) primary
- Phyllostomid bat eyes carry both UV-sensitive (S) and long-wave (L) cones; the authors conclude bats have the prerequisite for daylight vision, dichromatic colour vision, and UV vision.Bat Eyes Have Ultraviolet-Sensitive Cone Photoreceptors — PLOS ONE (PMC2712075) primary
- Fear-conditioning at 365 nm UV showed Scotophilus kuhlii and Cynopterus sphinx reacting to the light — direct behavioral evidence of cone-based UV vision in divergent bat lineages.Behavioral evidence for cone-based ultraviolet vision in divergent bat species — Zoologia (SciELO) primary
- BCI: at least seven insect-eating bat species show behavioral responses to ultraviolet light around 365 nm — a sensory edge over humans, who cannot see UV.Blind as a Bat? No Such Thing — Bat Conservation International analysis
Megabats (flying foxes) don't echolocate at all — they navigate entirely by large eyes and a keen nose.▰▰▰▱▱ likely3 points
Supports- Megabats (flying foxes) don't echolocate at all — they navigate entirely by large eyes and a keen nose.The truth about flying fox vision — Sunshine Coast Council analysis
- Only microbats can echolocate; megabats do not. Flying foxes rely on a keen sense of smell and good eyesight to navigate instead.The truth about flying fox vision — Sunshine Coast Council analysis
- Pteropodids lack laryngeal echolocation; only the genus Rousettus uses crude tongue-click echolocation. Megabats have large, front-facing eyes and rely on sight and smell.Megabat — Wikipedia (citing primary sources) summary
The myth's root: an 18th-century experiment showed blinded bats still hunted — but plugged ears left them helpless.▰▰▰▱▱ likely3 points
Supports- The myth's root: an 18th-century experiment showed blinded bats still hunted — but plugged ears left them helpless.Lazzaro Spallanzani Discovers Echolocation — History of Information summary
- In 1793 Spallanzani blinded wild bats; days later they were alive with insect-laden stomachs, while deafened bats blundered into obstacles in both dark and lit rooms.Lazzaro Spallanzani Discovers Echolocation — History of Information summary
- Jurine found that plugging bats' ears caused total disorientation; Spallanzani concluded the ears, not the eyes, were needed for oriented flight in the dark.Echolocation and Communication in Bats (Gould review) — SMU Fondren Science Series primary
Echolocation is a separate sense bats add on top of vision — and it was only named in 1944.▰▰▰▱▱ likely3 points
Supports- Echolocation is a separate sense bats add on top of vision — and it was only named in 1944.Donald Redfield Griffin — Encyclopaedia Britannica analysis
- Griffin, with Robert Galambos, discovered bats' ultrasonic orientation in the late 1930s and coined the term 'echolocation' in 1944.Donald Redfield Griffin — Encyclopaedia Britannica analysis
- Griffin's 1944 Science paper 'Echolocation by Blind Men, Bats and Radar' introduced the concept as a general method of perception by reflected sound.Echolocation by Blind Men, Bats and Radar — Science (1944) primary
Insect-eating echolocators actively use — and often prefer — their eyes when foraging.▰▰▰▱▱ likely3 points
Supports- Insect-eating echolocators actively use — and often prefer — their eyes when foraging.Use of vision in prey detection by brown long-eared bats, Plecotus auritus — Animal Behaviour (ScienceDirect) primary
- Brown long-eared bats given mealworms chose situations with visual cues, weighted vision above sonar, could not find prey by sonar alone, and used vision down to about 4 lux.Use of vision in prey detection by brown long-eared bats — Animal Behaviour (ScienceDirect) primary
- Boonman et al.: for distant landscape features vision detects out past 2 km versus ~50–100 m for sonar, while sonar wins for tiny insects — the two senses are complementary, not exclusive.It's not black or white — on the range of vision and echolocation in echolocating bats — Frontiers in Physiology primary
Bats blend sight and sonar moment to moment, weighting each according to the task at hand.▰▰▰▱▱ likely3 points
Supports- Bats blend sight and sonar moment to moment, weighting each according to the task at hand.Integrating vision and echolocation for navigation and perception in bats — Science Advances (PMC6594759) primary
- Egyptian fruit bats gave vision more weight when deciding where to fly but leaned on echolocation when approaching an obstacle — integration is task-dependent.Integrating vision and echolocation for navigation and perception in bats — Science Advances (PMC6594759) primary
- In big brown bats, presenting visual and acoustic obstacle cues together produced a stronger avoidance response than either modality alone.Visual cues enhance obstacle avoidance in echolocating bats — Journal of Experimental Biology primary
One bat reads the polarized light of the sunset sky to calibrate its internal magnetic compass.▰▰▰▱▱ likely3 points
Supports- One bat reads the polarized light of the sunset sky to calibrate its internal magnetic compass.A functional role of the sky's polarization pattern for orientation in the greater mouse-eared bat — Nature Communications primary
- Greater mouse-eared bats shown a sunset polarization pattern rotated by 90° later flew about 90° off the control group's heading — the first mammal known to use sky polarization.Bats use the evening sky's polarization pattern for orientation — Max Planck Society analysis
- Seventy female bats released about 20–25 km from their roosts in Bulgaria confirmed that the sky's polarization at dusk calibrates the bats' magnetic compass.A functional role of the sky's polarization pattern for orientation in the greater mouse-eared bat — Nature Communications primary
Vampire bats stack an infrared 'heat-sense' on top of vision — bats are sensory over-achievers, not sense-deprived.▰▰▰▱▱ likely3 points
Supports- Vampire bats stack an infrared 'heat-sense' on top of vision — bats are sensory over-achievers, not sense-deprived.Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats — Nature (2011) primary
- Vampire bats evolved infrared detection by splicing TRPV1 to lower its heat-activation threshold to about 30 °C in facial (trigeminal) nerves, letting them home in on warm blood.Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats — Nature (2011) primary
- BCI: vampire bats use thermal receptors to sense a victim's body heat from up to about 20 cm away.Blind as a Bat? No Such Thing — Bat Conservation International analysis
Disputed 2credible sources disagree
Did superior echolocation force bats to trade away their color and UV vision?▰▰▰▱▱ likely2 against5 points
Supports- Did superior echolocation force bats to trade away their color and UV vision?As Blind as a Bat? Opsin Phylogenetics Illuminates the Evolution of Color Vision in Bats — Molecular Biology and Evolution primary
- A color-vision gene study reported that bats with the most advanced echolocation appear to have traded UV vision for exquisite hearing.Just how blind are bats? Color vision gene study examines key sensory tradeoffs — Phys.org analysis
- The same study found multiple bat lineages independently lost a functional SWS1 (blue/UV) gene, framed as a sensory tradeoff accompanying specialized echolocation.Just how blind are bats? Color vision gene study examines key sensory tradeoffs — ScienceDaily analysis
Against- Counter-evidence: SWS1 is still functional in the high-duty-cycle echolocator Pteronotus parnellii, and across bats SWS1 loss correlates with cave roosting rather than echolocation type.As Blind as a Bat? Opsin Phylogenetics — Molecular Biology and Evolution primary
- Long-wave (M/LWS) vision stays functional and highly conserved across all bats sampled; only about 26 of ~115 species lost the SWS1 gene, so most bats keep working color vision.As Blind as a Bat? Opsin Phylogenetics — Molecular Biology and Evolution primary
Are bats colorblind? The simple label hides real variation across species.▰▰▰▰▱ likely2 against5 points
Supports- Are bats colorblind? The simple label hides real variation across species.As Blind as a Bat? Opsin Phylogenetics — Molecular Biology and Evolution primary
- Flying foxes lack the cone type for red wavelengths and are effectively red–green colorblind, seeing the world in blue and yellow tones with far fewer cones than humans.The truth about flying fox vision — Sunshine Coast Council analysis
- Some bat species have lost SWS1 function and so can no longer discriminate blues from violets.Blind as a Bat? No Such Thing — Bat Conservation International analysis
Against- Many bats are functional dichromats: phyllostomids carry both working S and L cones, giving them genuine dichromatic colour vision including UV.Bat Eyes Have Ultraviolet-Sensitive Cone Photoreceptors — PLOS ONE (PMC2712075) primary
- Across bats the long-wave opsin is conserved and the ancestral state was UV + long-wave dichromacy, so 'colorblind' fits only the subset of species that pseudogenized SWS1.As Blind as a Bat? Opsin Phylogenetics — Molecular Biology and Evolution primary
Debunked 1refuted by the evidence
'Blind as a bat' is false: bats are not blind. Every species has functional eyes and can see.Refuted by
USGS: 'No, bats are not blind.' They have small, very sensitive eyes that let them see in conditions we'd consider pitch black.
refuted2 against5 pointsThe claim rested on- 'Blind as a bat' is false: bats are not blind. Every species has functional eyes and can see.Are bats blind? — U.S. Geological Survey analysis
- English speakers have said 'blind as a bat' for centuries; the idiom rests on the old but mistaken belief that bats cannot see.Origin of: Blind as a bat — IdiomOrigins summary
- Aristotle likened the dazzled eyes of bats in daylight to a mind facing the most obvious truths — an ancient root of the bat-blindness trope.Blind As A Bat — Phrases.org.uk summary
Refuted by- USGS: 'No, bats are not blind.' They have small, very sensitive eyes that let them see in conditions we'd consider pitch black.Are bats blind? — U.S. Geological Survey analysis
- Bat Conservation International: despite the saying, all bats have functional eyes and can see; none are blind.Blind as a Bat? No Such Thing — Bat Conservation International analysis
Unresolved 1no settled answer
How bats actually sense polarized light remains an open mystery.▰▰▰▱▱ likely3 points
Supports- How bats actually sense polarized light remains an open mystery.Bats use the evening sky's polarization pattern for orientation — Max Planck Society analysis
- The lead researcher says further behavioural and physiological studies are needed to understand this new sensory capability — how bats detect polarization is unknown.Bats use the evening sky's polarization pattern for orientation — Max Planck Society analysis
- Reporting on the study, scientists conceded they have no idea what physiological mechanism lets bats perceive polarised light.Bats use polarized light to navigate — ScienceDaily analysis
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