January 4, 2009
Tree Frog Tadpoles, Costa Rica
Photograph by Paul A. Zahl
Within days of being deposited on a leaf overhanging a stream, tree frog eggs grow into recognizable tadpoles. Bulbous yolk sacs provide nourishment. As the wrigglers develop, the gelatinous outer membrane decomposes, perhaps triggered by a chemical change in the tadpoles. One by one, they slide off to a life of their own in the water.
(Photo shot on assignment for "Nature's Living, Jumping Jewels," July 1973, National Geographic magazine)
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