Bats and Whales Share Behavioral Similarities

The similarities of bats and whales, while they are both mammals, are not immediately obvious. One is tiny, sleeps upside down and flies. The other is huge and aquatic and breaths through a hole in its head.

But new research from Denmark suggests there is more in common between whales and bats than meets the eye.

The biosonar capabilities of both creatures have been shown to have remarkable similarities, despite the mammals' immense differences.

About 25 percent of all mammal species use some form of echolocation, including about 80 species of toothed whale and 1,100 species of bats. And despite their tremendous differences, a system of convergent evolution has led the disparate species to develop the same functional characteristics of their echolocation techniques.

"Our studies have shown that the sounds of bats and toothed whales are surprisingly similar. This is due to two things: First, all mammalian ears are developed in quite similar ways, and second, - which is the most surprising - the contradicting physical conditions in air and water along with the differences in size of the animals even out the differences, that you would expect in the sound frequency," said professor Annemarie Surlykke from University of Southern Denmark.

The researchers found that bats and toothed whales produce signals for echolocation in the same frequency range, from 10 to 200 kHz.

While they operate on the same frequency, the toothed whale is able to "see" much farther with its echolocation due to the properties the sound waves have in water. A sperm whale, for instance, can echolocate prey up to 500 meters away, while a bat can use echolocation to spot prey at a maximum of 10 meters.

Bats cover about one echo location distance per second, and must act swiftly when making choices of prey, where as the whale has more time to select prey due to its greater "field of vision" with its biosonar.

"The mechanism must play a key role but we do not yet know exactly which one," said professor Peter Teglberg from Aarhus University."There is a need for further studies and fortunately new technologies make it possible to track animals in the wild, study their behavior and compare these results with the knowledge we have from the laboratory".

The research is published in the journal Physiology