Study finds weta are like whales

22:36, Dec 12 2012
Whale weta
HEAR HEAR: Whales and weta have similar methods of hearing, researchers have found.

Oceans of difference separate a whale from a weta, but Auckland University scientists have discovered their method of hearing gives them common ground.

Researchers have discovered lipids, or compounds of fats and oils, in an Auckland tree weta's eardrums are similar to that of a whale's.

They believe the lipid compound in a weta's eardrum, on its front legs, works to efficiently transmit sound between ear chambers and helps amplify quiet sounds.

A whale is the only other creature known to use this method to hear, using lipid-filled cavities in its jaw to detect sound vibrations in the water.

It was already known weta use a liquid-filled cavity to transmit sound to its hearing organs, but until this research, it was presumed that liquid was insect blood.

The work was carried out by School of Biological Sciences researchers, who partnered with the New Zealand Institute for Plant and Food Research and Strathclyde University in Scotland.


They named the lipid-producing organ the Olivarius, after lead researcher Kate Lomas's son Ollie.

They discovered it using new tissue analysis and three-dimensional imaging techniques.

''The ear is surprisingly delicate so we had to modify how we looked at its structure and in doing so we discovered this tiny organ,'' Lomas said.

While the study was undertaken on the Auckland tree weta, researchers believe the same method of hearing is used by crickets and katydids, which are more famous for making chirping noises.

''We suspect that the use of lipid in insect ears is much more common than previously realised and other researchers in the field may need to rethink how these animals hear,'' said Auckland University associate professor Stuart Parsons.

However, why both weta and whales - creatures that couldn't be more physically different - use lipids to hear is still unknown.

 ''The short answer is we don't know, though it's likely they both converged on a very similar solution to a similar problem,'' Parsons said.

The research has been published in the PLOS ONE journal.

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