2012: Advent Biology: Bitten by an eel

by on December 1, 2012

Due to their aqueous environment, fish feed rather differently from terrestrial vertebrates. Though there are different methods of capturing prey, the most widespread mechanism for dealing with it once caught involves the use of suction: by creating a lower pressure inside than in the surrounding water using specialised structures and muscle groups to get food down the gullet. Even biting fish, as many predatory fish are, use this to get prey past their jaws once they have got their teeth into it.

This ancient mechanism isn’t common to all, though. The family of moray eels use an entirely different mechanism to get food once they’ve bitten it into their digestive system, and it’s more like something you’d expect to find in a sci-fi film than a fish tank. They belong to a class of fish who can move pieces of their skull and jaw separately, and have adapted part of the apparatus making up fish gills to become a second set of jaws, further down their throat. When the moray captures something in its teeth, these extra jaws are launched up into its mouth, grab onto the prey and draw it down into the eel’s gullet. They’re called ‘raptorial’ jaws, and there’s no escaping the eel once it’s got them into you.

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