How Moray Eels Swallow Their Prey
Moray eels have evolved one of the most remarkable feeding mechanisms in the animal kingdom. Unlike most fishes, they possess a second set of jaws, known as pharyngeal jaws, which can be projected from the throat into the mouth to grasp prey and pull it into the esophagus.
If this sounds familiar, it may remind you of the creature in the movie Alien. Indeed, the resemblance is striking, although nature developed this mechanism long before Hollywood did.
Pharyngeal jaws are not unique to moray eels. They are found in many groups of fishes, where they normally remain deep inside the throat and help process food after it has been swallowed. What makes moray eels exceptional is that their pharyngeal jaws are highly mobile and can be extended into the oral cavity to seize prey. No other fish is known to use this feeding strategy in the same way.
The photograph below shows both jaw systems in a Spotted Moray (Gymnothorax moringa). The large teeth visible in the center belong to the pharyngeal jaws. Once the prey has been captured by the outer jaws, the pharyngeal jaws move forward, grasp the prey, and pull it deep into the throat, where it can be swallowed.
The illustration on the right shows the pharyngeal jaws in their two positions: retracted inside the throat (top) and extended into the mouth (bottom).
This remarkable feeding mechanism allows moray eels to capture relatively large or slippery prey despite their narrow heads and the limited suction feeding that most other fishes rely on.
Further Reading
Mehta, R. S. & Wainwright, P. C. (2007). Raptorial jaws in the throat help moray eels swallow large prey: Nature 449, 79–82.