Sarcastic fringeheads are highly territorial and combative fish. When they encounter each other, they stretch open their mouths in a display that makes them seem ferocious and much larger than they actually are.
Did you know clownfish have teeth? They’re not very sharp, but these territorial fish won’t hesitate to bite intruders nearing in their anemone abode. Researchers also discovered that clownfish use their teeth to communicate with conspecifics by producing a chattering noise.