Whales and dolphins aren't the only swimmers to have mastered sound: many fish are chatty too, including the colorful clownfish of Finding Nemo fame, all 27 species of which make some form of chirping or popping sound while mating or fighting. In this week's Science, researchers report that the clownfish Amphiprion clarkii [above] produces such noises by raising its head, pressing its tongue down and snapping its lower jaws shut, causing its teeth to collide.