pineal eye

noun

1. an eyelike structure that develops from the pineal apparatus in certain cold-blooded vertebrates.

pineal eye

noun

1. an outgrowth of the pineal gland that forms an eyelike structure on the top of the head in certain cold-blooded vertebrates

pineal eye

/ pĭn′ē-əl,pī′nē-əl /

1. A sensory structure capable of light reception, appearing as a spot on the top of the head in lampreys, hagfish, amphibians, and some reptiles, especially the tuatara. Pineal eyes can contain a rudimentary cornea, lens, cone cells, and retina, and are thought to be sensitive to light and dark but not to be able to form images.

Word History and Origins

Origin of pineal eye¹

First recorded in 1885–90

Example Sentences

In the Lacertilia the pineal eye, if it be an eye, is better developed than in any existing vertebrate, though even in them there is no evidence of its being used for sight.

From Project Gutenberg

Albert was mercifully unconscious as it bent over him to inspect his prone body with a purple-lidded pineal eye that was blue with concern.

From Project Gutenberg

The pineal eye, as it is now named, once useful, long useless, has persisted as a fossil structure through a far extended line of development.

From Project Gutenberg

There it is, to be reckoned with, like the coccyx, the pineal eye, and the vermiform appendix.

From Project Gutenberg