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The camel has an extra eyelid - "wiper"
In the 3rd century the camel's eye. Two, with eyelashes, help protect the eyes from the sand, and the third, a very thin (nictitating membrane), it works as a kind of "wiper", washing away dirt from his eyes. This eyelid moves horizontally and not upside down. Furthermore, camel may be slightly visible therethrough. The sandstorm or a windy day the eyelids protect the eyes from the sand, with camel keeps going.
via factroom.ru
