…that’s a moray!
Yeah, I know — lousy pun (just be thankful I’m not subjecting you to a podcast with my singing in it!). Still, the September 6 issue of Nature brings some interesting news on moray eels and how they eat.
Interesting, particularly in the happy-to-be-at-the-top-of-the-food-chain way.
It turns out that most bony fishes have two sets of jaws — a normally-visible external one, and an internal (pharyngeal) one that’s essentially in the fishes’ throat. The fish pull in their food (generally via suction), then the pharyngeal jaw and its teeth are used to chew or grind the fishes’ food and help in swallowing it. If you’ve ever tried to retrieve a lure from a trout’s craw, you know just what I’m talking about here.
Well, it turns out that the moray eel is a fish of a different color. Moray eels have evolved to live and hunt in tight spaces, so they apparently have lousy suction for feeding (better suction would require more expansion of their mouths and necks than space would allow for). This has left people puzzled for years over just how they manage to feed effectively on large prey (and, for what its worth, morays are pretty much at the top of the food chain on reefs).
Using high-speed cameras and X-ray equipment, researchers at the University of California in Davis seem to have figured things out. Moray eels have highly mobile pharyngeal (throat) jaws — normally they’re located behind the eel’s skull, but when the eel is feeding, they go to work. So a moray eel first grabs food with its outer jaws (upper X-ray in this image), then the pharyngeal jaws move forward nearly the full length of the skull (lower X-ray) to grab the prey and bring it back for swallowing. Using a sort of ratcheting motion of the two sets of jaws, a moray eel can swallow even large prey in a fraction of a second. Nature has video of this in action here.
This unique physiology makes the moray’s extendable jaws the first set of pharyngeal jaws known to be used to help catch prey, rather than just to help swallow it. Well, at least in nature, anyway (vs. this). The UC Davis researchers now plan on trying to figure out just how the moray eel evolved such an interesting pair of jaws — while pharyngeal jaws are far from rare, the mobility of the moray’s set is an impressive thing.
A summary of the Nature article, source of the above images, is freely available (at least for a limited time) online here. The corresponding UC Davis press release is here, while the ScienceDaily rework of it is here. PZ Myers at Pharyngula has a nice writeup on it too.
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