Eyes and Functions
Most copepods have a single compound eye in the middle of their head, but this copepod, of the family Corycaeus, possesses two large cuticular lenses paired to form a telescope. Like most spiders, this wolf spider has eight simple eyes, two main eyes at the front and six smaller secondary eyes. The main eyes form images. The secondary eyes detect peripheral movement, and have a reflective tapetum lucidum which improves night vision. Holochroal eye of an Early Devonian trilobite Paralejurus sp. Schizochroal eye of a Devonian trilobite from the family Calmoniidae Horseshoe crabs have two primary compound eyes and seven secondary simple eyes. Two of the secondary eyes are on the underside.Most arthropods have at least one of two types of eye: lateral compound eyes, and smaller median ocelli, which are simple eyes. When both are present, the two eye types are used in concert because each has its own advantage. Flying insects can remain level with either type of eye surgically removed, but the two types combine to give better performance. Ocelli can detect lower light levels, and have a faster response time, while compound eyes are better at detecting edges and are capable of forming images.
Further information: Compound eye Further information: OcellusRead more about this topic: Arthropod Eye
Famous quotes containing the words eyes and, eyes and/or functions:
“They are friends; and friendly they guide him to prey
Yet never partake of the treat—
Eyes and brains to the dotard lethargic and dull,
Pale ravener of horrible meat.”
—Herman Melville (1819–1891)
“The river, right, tumbled into a cove;
But the map dashed the road along the stream
And we dotted man’s fishiest enthymeme
With jellied feet upon understanding love
Of what eyes see not, that nourishes the will:
We were fishers, weren’t we?”
—Allen Tate (1899–1979)
“In today’s world parents find themselves at the mercy of a society which imposes pressures and priorities that allow neither time nor place for meaningful activities and relations between children and adults, which downgrade the role of parents and the functions of parenthood, and which prevent the parent from doing things he wants to do as a guide, friend, and companion to his children.”
—Urie Bronfenbrenner (b. 1917)