In Ecuador's Yasuní National Park, butterflies sip a yellow-spotted river turtle's tears. The mineral-rich liquid helps the insects reproduce. In exchange, the reptile gets a good eye-cleaning. | Photo by Pete Oxford/Minden Pictures
"So she sat on, with closed eyes, and half believed herself in Wonderland, though she knew she had but to open them again, and all would change to dull reality."
—Lewis Carroll, Alice's Adventures in Wonderland