page_title: Eye
section_title: Pinhole eye
hierarchical_section_title: Eye / Types of eye / Simple eyes / Pinhole eye
caption_attribution_description: Nautilus pompilius&#160;L. 1758 English: Chambered Nautilus, at Pairi Daiza, Brugelette, Belgium
context_page_description: The eye is a round organ for sensing light so organisms can see. It is the first part of the visual system. About 97 percent of animals have eyes. Image-resolving eyes are present in cnidaria, molluscs, vertebrates, annelids and arthropods.
  In mammals, two kinds of cells, rods and cones, allow sight by sending signals through the optic nerve to the brain.
  Some animals can see light that humans cannot see. They can see ultraviolet or infrared light.
  The lens on the front part of the eye acts like a camera lens. It can be pulled flatter by muscles inside the eye, or allowed to become rounder. As some people get older, they may not be as able to do this perfectly. Many people are born with other small problems or get them later in life, and they may need eyeglasses to fix the problem.
  Like different cameras, different eyes have different abilities. They may have higher or lower resolution, the ability to detect small details. They may have different performance in low light; nocturnal animals can see better at night than daytime animals. They may have different ability to distinguish colors.
context_section_description: The pinhole eye is an advanced form of pit eye. It has several bits, most notably a small aperture and deep pit. Sometimes, the aperture can be changed. It is only found in the Nautilus. Without a lens to focus the image, it produces a blurry image. Consequently, nautiloids can not discriminate between objects with a separation of less than 11°. Shrinking the aperture would produce a sharper image, but let in less light.
caption: Nautilus has a pinhole eye
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