Bats navigate their environment using echolocation. They produce sound waves that are above the human hearing to catch their prey, according to the National Park Service. These sound waves are called ultrasound that bounces off objects in the environment.
Then the sound returns to the bats' ears which are now finely tuned to recognize their own calls. Scientists can translate these sounds into forms that human ears could hear and see.
But recently, a new study from the researchers of Tel Aviv University in Israel discovered that bats, unlike birds and other animals, are born with the knowledge of echolocation. On the other hand, other animals learn echolocation as they grow.
The researchers published their study, entitled "Echolocating bats rely on an innate speed-of-sound reference," in the Proceedings of National Academy of Sciences of the United States of America (PNAS).
Echolocation in Bats
Bats could be either large or small. Those large ones feed on fruits and find their way visually. But small bats eat insects and use echolocation to catch them.
According to Brittanica, echolocation is the process of producing sounds and listening to the reflected echoes from surfaces and objects in the environment. Bats and other animals who use echolocation use the information gathered using the technique to perceive the objects and their spatial relations.
Bats use their larynx to produce an intense, high-frequency sound that varies with species and per activity. When locating small insects, the emitted sounds are reflected with only a small fraction of their original energy. The sound further weakens as it travels through air before it reaches the ears.
High frequencies are essential to the sonar system of the bat to determine the nature of objects by reflected sounds.
But in the presence of noises, bats have a problem with echolocation and detecting reflected sounds. Therefore, they could obtain the information necessary for tracking and catching their prey.
Bats are Born Knowing Echolocation
Eran Amichai and Yossi Yovel at Tel Aviv University tested whether bats could adjust their echolocation to accommodate changes in the speed of sound.
New Scientist reported that the researchers trained eight adult Kuhl's pipistrelle bats (Pipistrellus kuhlii) to fly to a perch inside a chamber pumped with oxygen and helium. They observed that bats did not learn to adjust their echolocation.
Helium in the experiment served as a distraction to the bats, which caused them to aim short for the perch. Initially, researchers expected that the bats would fail, but then it continued showing that they never learned to adjust.
To further test their observations, they tried the same experiment with the pups instead of adults. They hand-reared 11 bats, wherein half of them are raised since birth in the helium-enriched chamber.
Then Amichai trained the pups to fly to the perch when they were old enough. But despite the environments where the pups were raised, they still fall short on aiming the perch in the helium-pumped chamber.
The experiments showed that the bats have a rigid, innate sense of the speed of sound. Given that all bats have the same brain structures for echolocation, scientists believe that their findings are valid in all bats.
Researchers believe that the innate sense of echolocation might be better than a flexible one that takes time to learn.
Read also: Echolocation
