Editor’s Note: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet initiative has ...

If you look closely at the Madonna della Vittoria, a Renaissance painting created in 1496 and hanging in the Louvre, you might notice something peculiar. To the left, just above the Virgin Mary's head ...

Sydney's salmon crest is as vivid as his presence. He's a large bird with a stocky build and a dangerous black, twig-splitting beak. His claws, too, could do some serious damage. The Monterey Zoo's ...