Researchers have found that moray eels use a second set of hidden jaws to help them swallow prey and pull it into their oesaphagus.
Rita Mehta and Peter Wainright of the University of California, Davis, studied the prey capture techniques of moray eels and found that they didn't use the suction response favoured by other teleosts.
Instead, moray eels have a second set of jaws in their pharynx which the moray uses in a previously unseen way.
While most fish use their pharyngeals jaws for crushing or grinding prey items, moray eels use theirs to reach forward and grab prey already being held by their oral jaws; from their they can pull it into the oesophagus and swallow it.
Their findings are reported in the latest issue of the journal Nature.
Protractible second jawsResearcher Rita Mehta of the University of California told Nature: "We filmed a lot of different types of eels trying to capture squid prey, or pieces of squid, as well as fish.
"Most fish feed using suction behaviour. So in order for a fish to create suction it must rapidly increase the size of its mouth cavity in all directions. And what this does is it creates negative pressure, so there is a fast flow of water in front of the fish's mouth. And so water enters the mouth cavity as well as the prey item.
"Most bony fishes are using suction, not only to capture their prey but also to help in swallowing their prey. And we found that eels have a very reduced capacity to employ suction. So what they have ended up doing is actually pretty amazing.
"They have a second set of jaws in their throat - their pharynx - that they protract up into their oral jaws. And once the oral jaws have captured their prey, the pharyngeal jaws, the second set of jaws, grab on to the prey and move the prey back into their oesaphagus."
The findings are the first ever to document any vertebrate using a second set of jaws to aprehend prey as well as to aid swallowing.
For more information see the paper: Mehta RS and PC Wainwright (2007) - Raptorial jaws help moray eels swallow large prey. Nature. Volume 449 Number 7158.