科学美国人60秒:Risky Ripples Allow Eavesdropping On Frisky Frog

Music is a tough way to make a living. Just ask the túngara frog. Its song can get it killed. Because the motion of its vocal sac when it produces its call also creates ripples in the surrounding water that predators can see.
 
To see how rivals—and predators—respond, researchers built decoys that produced mating calls, ripples or both.
 
When rival males heard the song and saw ripples, they doubled their competitive cries. But if the ripples came from less than 8 centimeters away, the rivals grew quiet, perhaps preparing to fight or flee.
Meanwhile, predatory bats preferred to attack when the model produced both audio and visual cues. But bats also reacted to ripples alone.

Now, túngara frogs shut up fast when a bat’s overhead. But the water’s continuing rippling can give the frogs away. The work is in the journal Science. [W. Halfwerk et al., Risky Ripples Allow Bats and Frogs to Eavesdrop on a Multisensory Sexual Display]

Seems that some animal communication is multi-sensory, and a signal's side effect can have unintended consequences. Like turning a love note into a death rattle.

—Sophie Bushwick