pigment cup eye

anatomy

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July 17, 2026

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A pigment cup eye is a simple eye found in many invertebrates. It consists of a cup-shaped structure lined with pigment cells and photoreceptors. This design allows the organism to detect the general direction of light, which is useful for basic environmental navigation, such as finding food. However, it offers very limited resolution, making it unsuitable for hunting or evading predators. These eyes are thought to have evolved independently numerous times across the animal kingdom. The optic cup, from which the retina develops, is a related structure in vertebrate eye development.12

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photoreception
Pigment cup eyes
In most of the invertebrate phyla, eyes consist of a cup of dark pigment that contains anywhere from a few photoreceptors to a few hundred photoreceptors. In most pigment cup eyes there is no optical system other than the opening, or aperture,…
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In most of the invertebrate phyla, eyes consist of a cup of dark pigment that contains anywhere from a few photoreceptors to a few hundred photoreceptors. In most pigment cup eyes there is no optical system other than the opening, or aperture,…
Read More