Dolphins, Insects Share Common Hearing Feature

Toothed whales like dolphins and insects share a common hearing system component, reveals a new study.

A team of international researchers led by University of Strathclyde, U.K., examined a New Zealand insect called Auckland tree weta and found they depend on a compound called lipid to hear the sounds around them. Until now, only toothed whales were known to have used this hearing system component.

"The discovery is interesting as previously only toothed whales were known to use this hearing system component, the lipid. There are many similarities in the use of lipids to amplify the sounds and help both animal groups to hear," James Windmill, of the University of Strathclyde's Center for Ultrasonic Engineering, said in a statement.

"We don't know why animals who are so far apart in evolutionary terms have this similarity, but it opens up the possibility that others may use the same system component."

Sound in the Auckland tree weta is known to travel through a liquid-filled cavity that helps it reach the hearing organs. It was presumed that the liquid was the insect's blood.

But now researchers have found that it is indeed the lipid (a compound that includes oils and fats) which plays a significant role in transmitting sounds between compartments of the ear and possibly help in amplifying quiet sounds.

"In the weta, as in other members of the Ensiferan group which includes katydids and crickets, sound is detected by ear drums on the front legs," said Kate Lomas, from the University of Auckland, New Zealand.

The research team discovered a small organ in the insect's ears using tissue analysis and three-dimensional imaging techniques. They found that the organ helps in producing the lipid. It has been named olivarius after Lomas' son Ollie.

Experts believe that the lipid compound is also present in insects like crickets and katydids apart from the Auckland tree weta, as they are all members of the same biological class.

The findings of the study are published in the journal PLOS ONE.