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Eagle Vision
#1
Two questions;

1) Does anyone know the acuity of the average eagle?

I think I read somewhere it was 20/5, but that means mere humans like us can easily acquire eagle vision!! (With bates training) 2) Also I would like to ask; which creature has the most powerful vision?
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#2
The eagle and hawk, which are predatory birds, have the best vision acuity of any animal. Vision acuity itself is unknown to me... Eagles can spot a hare from a mile away, but there have been given estimations of 2-4 times better than human eyesight (acuity not given regarding human eyesight).

Here are some facts to ponder:

1. The Australian aboriginals have similar to 20/5 eyesight, but 1 in 4 have vision problems.  <!-- m --><a class="postlink" href="http://www.abc.net.au/science/k2/trek/4wd/tinykids.htm">http://www.abc.net.au/science/k2/trek/4wd/tinykids.htm</a><!-- m -->
2. The rings of Saturn were known before Galileo's time. Western society cannot explain this.

Quote:... The statue of Saturn on the Roman capitol had bands around its feet,(6) and Macrobius in the fifth century of our era, already ignorant of the meaning of these bands, asked: “But why is the god Saturn in chains?�

In the Egyptian legend Isis (Jupiter) swathes Osiris (Saturn). The Egyptian apellative for Osiris was “the swathed.� (7)

In the Zend-Avesta it is said that the star Tistrya (Jupiter, later Venus) keeps Pairiko in twofold bonds.(8) Saturn is encircled by two groups of rings—one larger and one smaller, with a space in between. To see this a better telescope than that used by Galilei or that used by Huygens is needed; the twofold structure of the girdle was first observed in 1675.(9)

The rings of Saturn were known also to the aboriginees of America before Columbus discovered the land; this means also before the telescope was invented at the beginning of the seventeenth century. An ancient engraved wooden panel from Mexico shows the family of the planets: one of them is Saturn, easily recognizable by its rings.(10)

Nor were the Maoris of New Zealand ignorant of them: “One of the great mysteries connected with Saturn is the still unanswered question of how the ancient Maoris of New Zealand knew about her rings—for there is evidence that they did have a Saturnian ring legend long before the days of Galileo.� (11) ...

Citation: <!-- m --><a class="postlink" href="http://www.varchive.org/itb/rings.htm">http://www.varchive.org/itb/rings.htm</a><!-- m -->
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#3
Absolutely awe inspiring...  Smile

(I'm reading the articles)

Well... hah! Soon I will beat these aborigines, for I shall observe, with naked eye, planets... in other galaxies... MUAHAHAHA! *insert darth vader theme* GAHAHAHAHAHAAAAA....*join the dark side, by palming! *

<!-- m --><a class="postlink" href="http://moviethemes.net/music/starwars/darth-vader.mid">http://moviethemes.net/music/starwars/darth-vader.mid</a><!-- m -->
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#4
Wow, some pretty cool information:

"Eyesight

All eagles are renowned for their excellent eyesight, and the bald eagle is no exception. They have two foveae, or centers of focus, that allow the birds to see both forward and to the side at the same time. Bald eagles are capable of seeing fish in the water from several hundred feet above, while soaring, gliding, or in flapping flight. This is quite an extraordinary feat, since most fish are counter-shaded, meaning they are darker on top and thus harder to see from above. Fishermen can confirm how difficult it is to see a fish just beneath the surface of the water from only a short distance away.

Young bald eagles have been known to make mistakes, such as attacking objects like plastic bottles floating on or just below the surface of the water. Bald eagles will locate and catch dead fish much more rapidly and efficiently than live fish, because dead fish float with their light underside up, making them easier to see.

Eagles have eyelids that close during sleep. For blinking, they also have an inner eyelid called a nictitating membrane. Every three or four seconds, the nictitating membrane slides across the eye from front to back, wiping dirt and dust from the cornea. Because the membrane is translucent, the eagle can see even while it is over the eye.

Eagles, like all birds, have color vision. An eagle's eye is almost as large as a human's, but its sharpness is at least four times that of a person with perfect vision. The eagle can probably identify a rabbit moving almost a mile away. That means that an eagle flying at an altitude of 1000 feet over open country could spot prey over an area of almost 3 square miles from a fixed position.

Hearing

Eagles are not distinguished for their hearing, but this does not mean that they have poor hearing. Diurnal (active by day) birds of prey like hawks and eagles use their hearing to locate prey or other birds, but the sharpness is not as essential as in some owls, which can locate prey in the dark only by their sound."

-baldeagleinfo.com

"Q.Why does "eagle eye" describe sharp eyesight?

A. An eagle’s eye is extra keen because the soaring bird must rely on extremely sharp vision to spot prey on the ground. Compared with a human eye, the eagle eye has more than four times the number of light-sensitive cells ( rods and  cones) in the inner back eye structure known as the  retina where images are processed. The eagle’s eye also is disproportionately large, and can see in full color.

The eagle can see a distant scene in extremely fine detail because of two internal eye structures ( foveae) within the retina where light-sensitive cells are concentrated. In contrast, the human eye has only one fovea. The eagle eye also can rapidly adjust its focus, allowing keen vision at all distance ranges."

-vision.about.com/od/opticsvisiontheory/f/eagleeye.htm

"EAGLE EYES

Imagine a nesting adult female bald eagle near the top of a tall pine tree located two hundred yards from the lakeshore intently watching the water. Suddenly she leaves the nest and after a few strokes of her powerful wings is over the water. She swoops down, snatches a fish from just below the surface with her talons and then returns to the nest to consume her prey.

Such an event would not be possible were it not for the bald eagle's remarkable eyesight. Sight is an eagle's most important sense. Scientists believe that an eagle's vision is as much as six times sharper than a human's even though the eyes are approximately the same size. The relatively large eye to head size is not obvious because most of the eye socket is surrounded by the skull. In fact the eye consumes so much of the skull that there is little room left for the muscles that move the eye. The eagle can compensate for the lack of eye mobility by rotating its neck. The large number of cervical vertebrae in the neck enable it to sweep a 270 degree arc.

Even though an eagle's eyes are located on the side of the skull, they protrude outward and their position is far enough forward to provide an overlapping field of view. This allows a degree of binocular vision and its associated depth perception. The ability to accurately perceive distances is critical when diving for prey and snatching it with talons.

The cornea or outer surface of the eye is protected by a ring of bones called the sclerotic eye ring and by two eyelids. The outer eyelid is similar to a human's and is closed from the bottom when sleeping. The inner transparent eyelid is called a nictitating membrane. It protects and keeps the eye moist and clear by flicking across the eye sideways every three or four seconds. Eagle parents often pull the membranes over their eyes when feeding their young. This prevents the eye from being accidently injured by the chicks when they lunge for their food.

The extremely soft lens of the eye allows for rapid accommodation. This ability to quickly refocus between near and far assists in prey identification and self protection. In addition, the eyes are partially atonomous which allows some independent monocular vision to the sides.

Bald eagle eyes are imposing, and change in color over several years from a chick's dark brown to a mature's buff or bright yellow.

Eagles have fairly distinctive eyebrows that provide additional protection from injury. The eyebrow also shades the eye from the glare of the sun above. This is especially beneficial to a bird that spends a significant amount of time soaring the skys in search of prey below. When the nictitating membrane is closed it provides enough filtration to allow an eagle to spot an overhead intruder even when looking directly at the sun.

An eagle's retina differs from a human's in several ways. The human retina has a single depression called a fovea. It contains the highest concentration of sensory cells and provides the maximum optical resolution. Not only does the eagle eye fovea contain a denser concentration of sensory cells (for a larger and sharper image) but there are two of them in each eye! One fovea optimizes monocular vision to the side and the other optimizes binocular vision to the front.

An eagle's retina contains rods for faint light perception and cones for color perception just like a human's. However, the eagle retina has many more cones than rods. When there is ample light an eagle can distinguish well hidden prey from it surroundings. In low light conditions, the ability to differentiate color diminishes and the eagle sees objects in varying shades of gray. The reduced number of rods limits the eagle's night vision and explains why the eagle normally hunts after first light or during the day.

Eagles (along with all birds, fishes and reptiles) have a peculiar structure in the eye called a pectin. It is a fan shaped tissue that is attached to the retina and protrudes into the central part of the eye. It is full of blood vessels and may supply oxygen to the retina.

An eagle's eye is a complex structure which provides a truly remarkable sense of sight."

-members.aol.com/EglAdvocat/ornith.html#eyes

I don't know why, but reading this sort of stuff really motivates me, even more than success anecdotes! Perhaps we should move from the study of the bates method, and learn even more about how we can sharpen our vision by studying animals like the hawk and eagle... Maybe one day we will learn to have two foveas - damn that would be too cool. Cloning - anyone?
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