When ostriches look at you it is hard to avoid their eyes, that is probably because of their rather sinister, long snake-like neck and serious unflinching expression. Then again it could be because, as the largest bird in the world, they have the largest eyes of any bird in the world. In fact, this is not the only impressive statistic about an ostrich's eyes. At 2in (5cm) in diameter, measured front to back, from the center of the cornea to the retina, they are five times bigger than the human eye and bigger than that of any land animal. Only the grandest squids in the ocean have larger eyes. Furthermore, comparing the largest to smallest in the bird world, the eye of the ostrich is about as big as the whole body of the smallest bird in the world - the bee hummingbird. Altogether, it is a remarkable organ. And their mothers don't teach them not to stare. A curious bird, they sometimes like to have a good, up-close look at things until they are good and satisfied with their inspection.

The ostrich needs large eyes for its terrestrial lifestyle sharing the savanna as it does with an alarming army of fearsome predators. The flightless bird is famed for its running prowess, reaching speeds of 45mph (70kph) when pressed, which is fast enough to escape most predators. Those big, long powerful legs were born to run. But it has to see what to run from first. Standing up to 9ft (2.75cm) tall, it enjoys an excellent view over the grassland and bush. Meanwhile, the high number of photoreceptor cells in the eye, combined with the sheer size of the image from the lens, means the ostrich can see in phenomenal detail. Indeed it's eye is at the size limit of usefulness, any larger and destruction would begin to distort the image.

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