A new sensory organ has been discovered in the jaws of giant whales that may help them “lunge-feed” to swallow huge numbers of crustaceans and small fish.

The grapefruit-sized organ has protrusions filled with nerves and is suspended in a gel-like material.

Scientists believe it responds to jaw rotation when a whale opens and closes its mouth, and expands its vast throat pouch to take in water, but they are still trying to understand precisely how this lunge-feeding mechanism works.

“We think this sensory organ sends information to the brain in order to co-ordinate the complex mechanism of lunge-feeding, which involves rotating the jaws, inverting the tongue and expanding the throat pleats and blubber layer,” said lead researcher Dr Nick Pyenson, from the Smithsonian Institution in Washington, DC.

Rorqual whales, which include blue, fin, minke and humpback whales, feed by lunging forward and gulping more than their own body weight of water.

Millions of krill, tiny crustaceans, and small fish are then filtered out in a process that takes seconds.

Co-author Professor Bob Shadwick, from the University of British Columbia in Canada, said: “In terms of evolution, the innovation of this sensory organ has a fundamental role in one of the most extreme feeding methods of aquatic creatures.

“Because the physical features required to carry out lunge-feeding evolved before the extremely large body sizes observed in today’s rorquals, it’s likely that this sensory organ – and its role in co-ordinating successful lunging – is responsible for rorquals claiming the largest-animals-on-Earth status.

“This also demonstrates how poorly we understand the basic functions of these top predators of the ocean and underlines the importance for biodiversity conservation.”

http://www.iol.co.za/the-star/grapefruit-sized-organ-helps-whales-swallow-big-mouthfuls-1.1304478