Named for the undulating waves of its broad, fleshy appendages—called parapodia—lettuce sea slugs appear in a range of colors ...

Each killer whale has a distinct pattern of pigmentation behind its dorsal fin. How do these patterns vary around the world?

The wooden fishing boat chugs across Comau Fjord, a finger of dark water wedged between the snowy peaks of Chilean Patagonia. A Chilean flag flaps in the wind above a hand-painted black cormorant on ...

Removing dams from the Klamath River in Northern California seems like a clear win for fish and rivers. Why do some locals hate it?

Removing dams from the Klamath River in Northern California seems like a clear win for fish and rivers. Why do some locals hate it?