Photoreception

Introduction
Diversity of eyes
- Single-chambered eyes
  - Pigment cup eyes
  - Pinhole eyes
  - Lens eyes
  - Corneal eyes
  - Concave mirror eyes
- Compound eyes
  - Apposition eyes
    - Image formation
    - Neural superposition eyes
    - Wavelength and plane of polarization
    - Differences in resolution
  - Superposition eyes
    - Refracting, reflecting, and parabolic optical mechanisms
    - Optics of superposition eyes
Structure and function of photoreceptors
- Photopigments
- Neural transmission
Adaptive mechanisms of vision
- Vision and light intensity
- Eye movements and active vision
Central processing of visual information
Evolution of eyes

References & Edit History Quick Facts & Related Topics

Images & Videos

optical arrangements of eyes among nocturnal, arhythmic, and diurnal animals

Diagram of an opossum eye in cross-section showing a large lens and labeled retina, illustrating how the eye's structure enhances night vision by gathering more light.

An adult Virginia opossum (Didelphis virginiana) carries several young on its back while walking outdoors.

Discover how scientists have recreated the benefits of insects' compound eyes as compound lenses

image formation in apposition and superposition eyes

Diagram showing the structure of rod and cone cells in the eye, with labeled parts including outer and inner segments, mitochondria, nucleus, and synapse. A detailed view of the rod's outer segment highlights lamellar particles, free-floating disks, ciliary fibrils, and membrane folds, illustrating photoreceptor anatomy involved in vision.

At a Glance

photoreception summary

Related Questions

How are the disk membranes in rods different from those in cones?
How can mutations in the RHO gene affect vision?
How do bees use ultraviolet, blue, and green photoreceptors for colour vision?
How do bipolar cells relay signals from photoreceptors in the retina?
How do cone cells enable humans to see different colours?
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How do rods and cones differ in their responses to light?
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How is retinal related to vitamin A?
How many rods and cones are found in a typical human retina?
What are the two main parts of a rhodopsin molecule?
What happens to rhodopsin in bright light?
Where are rods and cones located in the human eye?
Why are photopigments packed densely in rod and cone outer segments?
Why are rod cells more useful than cone cells in dim light?
Why are the axons of ganglion cells part of the optic nerve?
Why can many birds and fish detect ultraviolet light?
Why do ganglion cells respond strongly to local contrast rather than uniform light?
Why do humans see most colours through the combined activity of different cone cells?
Why do rod cells not provide colour vision?
Why do snakes that locate warm prey with infrared radiation not use photoreceptors for that task?
Why do sodium channels close in vertebrate photoreceptors exposed to light?
Why do vertebrate photoreceptors release more neurotransmitter in darkness?
Why does rhodopsin bleaching reduce the sensitivity of rod cells?
Why does the fovea provide the sharpest human vision?
Why does vitamin A deficiency cause night blindness?
Why is the blind spot unable to detect light?
Why is the retina considered an extension of the brain?
Why is photosynthesis important?
What is the basic formula for photosynthesis?
Which organisms can photosynthesize?

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External Websites

National Center for Biotechnology Information - PubMed Central - Intensity and The Process of Photoreception

Photoreception

biology

Also known as: light reception

Written by

Michael Land

Emeritus professor of neurobiology, Sussex Vision Laboratory, Sussex Centre for Neuroscience, University of Sussex, Brighton, England.

Michael Land

Fact-checked by

Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

Britannica Editors

Last updated

Nov. 6, 2026 •History

Photoreception, any of the biological responses of animals to stimulation by light. In animals, photoreception refers to mechanisms of light detection that lead to vision and depends on specialized light-sensitive cells called photoreceptors, which are located in the eye. The quality of vision provided by photoreceptors varies enormously among animals. For example, some simple eyes such as those of flatworms have few photoreceptors and are capable of determining only the approximate direction of a light...

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