The Pharyngeal Innovation of Moray Eel's

Yesterday Rita Mehta came to the MVZ to present her research in a talk entitled "Pharyngeal Innovation in Moray Eels: A novel mechanism for swallowing large prey". This research is garnishing a large amount of attention from both the popular press and in the form of the Nature paper, which is published today. She gave a very mice talk that was detailed enough for those who know something about Moray's (Muraena retifera) and their mouth parts, but simple enough for people like me that had no idea what Pharyngeal Jaws were...

Her research is motivated my the question "how to large elongate obligate predators sustain themselves through such a small gape". She draws on more well well known examples such as snakes....

"This mechanism of prey transport is behaviourally and functionally convergent to prey transport in snakes. Snakes transport prey by alternating ratcheting movements of the left and right sides of their upper jaws to advance their head over prey^{12, 13}. Oral jaw ratcheting is coupled with flexion and extension of their cervical and thoracic vertebrae¹³. Ratcheting enables snakes to maintain a bite on their prey with one side of their upper jaws while the opposing side moves over the prey. Morays transport prey using alternating movements of the oral and pharyngeal jaws followed by flexion and extension of the anterior region of the vertebral column. The dual-jaw system of morays functions to alternate oral biting with pharyngeal biting, allowing morays to maintain a grip on their prey at all times, as snakes do."

Basically, she found that while most Telosets feed by using suction in some way morays are poor suckers. Instead, they grasp prey with their outer jaws, then the pharyngeal jaws — which normally sit behind the skull — reach forward into the mouth to grasp the food and carry it back for swallowing. What the heck is a pharyngeal Jaw?? Here is the photo..

The 1st image is the jaw in the normal anatomical position. The 2nd image, below is the jaw in the "feeding position" It's pretty hard to miss, but see the superior tooth plate indicated by the error.

One of the things that struck me most during her talk was how mobile that jaw is... It moves really far- and quickly...






















Here is the video... See the pharyngeal jaws coming out and grabbing the prey?



Way cool huh?

Here are some SEM images of the jaws themselves... It seems pretty clear that these teeth are for grasping- not chewing or crushing.

See press coverage at Reuters, NPR, and PhysOrg

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I bet that there will be more people commenting on this, but later in the day....