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Pineal eye

From Biology-Online Dictionary | Biology-Online Dictionary
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Definition

noun, plural: pineal eyes

An eye-like structure that develops from the pineal gland and is located on the top of the head in certain animals, such as reptiles


Supplement

A pineal eye pertains to the structure that can be found on top of the head in certain animals, such as reptiles. It resembles the eye that is why it is sometimes referred to as the third eye. It is an outgrowth of the pineal gland. The pineal gland is an endocrine gland and part of the epithalamus. The pineal gland is associated with the regulation of circadian rhythmicity. It is also responsible in the production of hormone for thermoregulation. Birds and mammals have a pineal gland but not the pineal eye. One of the animals that have pineal eye is the tuatara. Tuatara are nocturnal lizard-like reptile of the genus Sphenodon and can only be found in New Zealand. Their pineal eye has small lens and retina. The pineal eye may be found in certain species of lizards, frogs, lampreys, tuna, and pelagic sharks. Certain salamanders and zebrafish also have similar light-sensitive but poorly developed structure. It is referred to as parapineal gland. The pineal eye may be photoreceptive. Its ability to detect light is different from the way the rod cells and cone cells of a typical vertebrate eye detect light.


Synonym(s):

  • third eye
  • parietal eye

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