Thanks to Live Science for this:
Name: Sarcastic fringehead (Neoclinus blanchardi)
Where it lives: From San Francisco, to Baja California, Mexico
Usually found on rocky reefs or sandy seabeds between around 9 and 240 feet (3 to 73 meters) below the water’s surface, these solitary fish make their home inside shells, clam burrows, rock crevices.
When fighting over territory, the fish try to intimidate their opponents by opening their jaws wide to display the bright colors inside. “The mouth’s intimidating coloration, combined with the extreme nature of its size (which may be as much as four times its closed size) allows the larger male to establish dominance over the smaller,” according to the conservation organization Oceana.
If the competitor isn’t scared off by the giant, colorful mouth display, the pair will launch into mouth-to-mouth combat, pressing their wide mouths together. “While this may look like the fish are kissing, they are in fact aggressively defending their territory from each other,” Inamura said. The bigger the fish’s mouth, the more chance it has of winning this battle.
