Fishes are a bit unsubtle when it comes to teeth. In their various grabbing, biting, crushing and grinding exercises, many fishes employ teeth not just in their jaws, but also elsewhere, such as on the palate or their gill arches. Indeed, the gills can play an important role in moving food from the mouth down into the stomach. Many fishes have these so-called “pharyngeal jaws”, but it is only in the moray eels that they are truly worthy of the name.

X-ray pictures showing the moray eel's pharyngeal jaws (a) in resting position and (b) in biting position.
X-ray pictures showing the moray eel’s pharyngeal jaws (a) in resting position and (b) in biting position.

Rather reminiscent of the xenomorph from the Alien movie franchise, the moray eel’s pharyngeal jaws can be moved forwards to grab a prey in the oral cavity and pull it further in. This is a clever little trick, for whereas many fishes suck their prey into their mouths, moray eels are incapable of doing so. Moreover, they tend to eat rather big animals, a bit like some snakes do. In order to swallow big prey items whole, the moray eel utilises its ability to move the two sets of jaws independently. Thus, it grabs its prey with its front jaws, then the pharyngeal jaws grab it too, and the front jaws release. Then the pharyngeal jaws pull the prey further in, after which the front jaws grab it again and the pharyngeal jaws release. And so, step by step, the eel can make its victim go all the way in without ever having to release it.

Keep that in mind the next time you watch Disney’s The Little Mermaid and see Flotsam and Jetsam, Ursula’s moray eel minions. Poor Flounder; as if they weren’t creepy enough without that extra set of jaws.

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