Welcome to Fish Fridays, our weekly value added segment about all things fishy. Today I wanted to highlight Moray eels and a really cool morphological adaptation that this critter has. It has to do with their jaws!

Vertebrate jaws are of course a product of evolution, and all vertebrates, even humans, have at some point in development serially repeated array of pharyngeal arches. We retain only the most anterior arch to form our jaw.  Fish have this jaw as well, but they retain the other arches in their hardened form as structures that support the gills, sometimes supporting additional teeth as well.  But imagine if the most anterior arch wasn't the only that developed into a fully functioning jaw? Then you would have a series of jaws! This is only the beginning of why eels jaws are unique. 

Sometime around 2008, Rita Mehta from UC Davis found that eels feed like no other fish.  Like many fish species, they have structures inside their throat called pharyngeal teeth that aid in processing food, but Moray's pharyngeal teeth have evolved to such an extent that they function as a second set of jaws, with the ability to extend forward in the mouth and grab food caught by the primary jaws. This of course is reminiscent of the creature created by Giger that was used in the movie Aliens, and thus the Moray eel has gotten even more attention as an ominous predator.  

Apparently the closest thing to this elaborate set of jaws exists in some snakes.  See the video below with the UC Davis researcher who discovered this.

Ben Labay is a "fish-geek" and research associate for the Texas Natural History Collections at UT Austin

See his fish art at: www.inkedanimal.com