Function
The lizard-like reptile tuatara has a "well-developed parietal eye, with small lens and retina". Parietal eyes are also found in lizards, frogs and lampreys, as well as some species of fish, such as tuna and pelagic sharks, where it is visible as a light-sensitive spot on top of their head. A poorly developed version, often called the parapineal gland, occurs in salamanders and in fish such as zebrafish. In birds and mammals the parietal organ (but not the pineal gland) is absent.
Read more about this topic: Parietal Eye
Famous quotes containing the word function:
“It is the function of vice to keep virtue within reasonable bounds.”
—Samuel Butler (1835–1902)
“The intension of a proposition comprises whatever the proposition entails: and it includes nothing else.... The connotation or intension of a function comprises all that attribution of this predicate to anything entails as also predicable to that thing.”
—Clarence Lewis (1883–1964)
“My function in life is not to be a politician in Parliament: it is to get something done.”
—Bernadette Devlin (b. 1947)