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Blue eye lack pigments found in other colored eyes including...

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Caption: Blue eye lack pigments found in other colored eyes including melanin which produces dark eyes, The pupil is an opening located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In optical terms, the anatomical pupil is the eye's aperture and the iris is the aperture stop. The image of the pupil as seen from outside the eye is the entrance pupil, which does not exactly correspond to the location and size of the physical pupil because it is magnified by the cornea. On the inner edge lies a prominent structure, the collarette, marking the junction of the embryonic pupillary membrane covering the embryonic pupil. The pupil is the central transparent area, showing as black. The grey/blue area surrounding it is the iris. The white outer area is the sclera, the central transparent part of which is the cornea. The iris is a contractile structure, consisting mainly of smooth muscle, surrounding the pupil. Light enters the eye through the pupil, and the iris regulates the amount of light by controlling the size of the pupil. In humans the pupil is round, but other species, such as some cats, have slit pupils. The iris contains two groups of smooth muscles; a circular group called the sphincter pupillae, and a radial group called the dilator pupillae. When the sphincter pupillae contract, the iris decreases or constricts the size of the pupil. The sensory pathway (rod or cone, bipolar, ganglion) is linked with its counterpart in the other eye by a partial crossover of each eye's fibers. After 25 years of age the average pupil size steadily decreases, though not at a steady rate. At this stage the pupils do not remain completely still, therefore may lead to oscillation, which may intensify and become known as hippus. As the body ages, age wrinkles, eye wrinkles, eye age wrinkles, sometimes called crows feet, gradually appear. Virginia, USA; Eye of Rob Simpson, model released, Eye09436DzS_ARS.jpg
Scientific name: Homo sapiens
Location: Virginia, VA, United States of America
Copyright: © Ann & Rob Simpson
Agent: www.agpix.com/snphotos
Release Available:
AGPix ID: AGPix_RoAnSi18_0699
Photo Alignment: 35mm (horizontal)
Comments: Ann & Rob Simpson - Simpson's Nature Photography, 1932 E Refuge Church Rd., Stephens City, VA 22655 Ph & Fax 540 869 2051 - AnnRobSimpson@snphotos.com - www.agpix.com/snphotos

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Ann & Rob Simpson
1932 E Refuge Church Rd.
Stephens City VA 22655-9607

Phone:
540 869-2051

Fax:
540 869-2051

Email:
annrobsimpson@snphotos.com

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www.snphotos.com

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white-tipped sicklebill, Eutoxeres aquila This bill is apparently specially adapted to obtain nectar from the flowers of Heliconia and Centropogon plants. Sicklebills feed by "trap-lining" between favorite plants and, unlike most other hummingbirds, actually perch on the flowers while feeding. White-tipped Sicklebill occurs in the understory of humid forest in foothills and on mountain slopes from Costa Rica south to northern Peru; Panama, Central America, SicklebilW43851xrs.tif
© Ann & Rob Simpson
white-tipped sicklebill, Eutoxeres aquila This bill is apparently specially adapted to obtain nectar from the flowers of Heliconia and Centropogon plants. Sicklebills feed by "trap-lining" between favorite plants and, unlike most other hummingbirds, actually perch on the flowers while feeding. White-tipped Sicklebill occurs in the understory of humid forest in foothills and on mountain slopes from Costa Rica south to northern Peru; Panama, Central America, SicklebilW43851xrs.tif
© Ann & Rob Simpson