Though they evolved separately over millions of years in different worlds of darkness, bats and toothed whales use surprisingly similar acoustic behavior to locate, track, and capture prey using echolocation, the biological equivalent of sonar. Now a team of Danish researchers has shown that the acoustic behavior of these two types of animals while hunting is eerily similar.
If evolution is true then bats and whales would have been evolving independently for millions of years. And yet they both constructed a sonar capability which involves transmitting loud signals while receiving incredibly weak signals, adjusting the signal parameters in real time, processing the received signals, and so forth. They even share the same range of ultrasonic frequencies:
Bats and toothed whales (which include dolphins and porpoises) had many opportunities to evolve echolocation techniques that differ from each other, since their nearest common ancestor was incapable of echolocation. Nevertheless – as scientists have known for years – bats and toothed whales rely on the same range of ultrasonic frequencies, between 15 to 200 kilohertz, to hunt their prey.
And that similarity is in spite of the different environments:
This overlap in frequencies is surprising because sound travels about five times faster in water than in air, giving toothed whales an order of magnitude more time than bats to make a choice about whether to intercept a potential meal.
But that is not all. The bat and whale also use similar strategies for adjusting their signals while homing in on prey:
Bats increase the number of calls per second (what researchers call a “buzz rate”) while in pursuit of prey. Whales were thought to maintain a steady rate of calls or clicks no matter how far they were from a target. But the new research shows that wild whales also increase their rate of calls or clicks during a kill – and that whales’ buzz rates are nearly identical to that of bats, at about 500 calls or clicks per second.
It is another example of a complex design evolution can only speculate about, and once again the evolutionary tree fails to predict its pattern.