In the wild, survival means adaptation—and for some animals, that means changing gender! From fish and amphibians to reptiles and invertebrates, these creatures can switch sexes to thrive in their ...

Learn all you wanted to know about animals with pictures, videos, facts, news, and more. Composite photograph by Joel Sartore, National Geographic Photo Ark Amphibians ...

Some species of birds like geese save energy by flying in close formation. Airliners could use a similar trick to burn less ...