The Amazon's largest fish makes a comeback

Even in the most biodiverse rainforest of the world, the pirarucu stands out: It can weigh up to 440 pounds, by far the largest of 2,300 known fish species in the Amazon.

Emperor penguins now listed as threatened species

Emperor penguins will now receive new protections under the Endangered Species Act after the U.S. Fish and Wildlife Service says climate change is threatening to eradicate the species.