For those of you who don't read National Geographic, here's an interesting "fun fact" from the latest March issue. . . You think the slimy villain from the Alien movies is the only creature with a second set of jaws? Well, how about the Moray Eel?
Many divers are familiar with the moray's threatening display of sharp teeth - a pose that comes about from the eel's breathing, as it doesn't have large flapping gill structures like bony fishes - and that these rear-facing teeth are designed to hold fast to its prey. But did you know that it has a second set of jaws that spring forward and assist in pulling the prey down its esophagus? This all takes place deep in the eel's throat and though it seems like something right out of a sci-fi thriller, it's actually a very efficient method of food transport for an animal that doesn't have the ability to gulp food down - like the vacuum motion you see with many other fish.
National Geographic reported that researchers from the University of California at Davis have studied this ability using x-ray and high-speed video (see photo) and it is apparently the first known mechanism of its kind in a vertebrate. Snakes get close, with hinged jaws that can slowly ratchet their prey down the gullet, and it's an example of evolutionary convergence - the development of a similar solution between animals facing the same problem.
As a volunteer diver at the Aquarium of the Pacific, me and my fellow team mates would feed the aquarium's eels and watch how they would grab a large sardine or squid perpendicular, turn it towards their throat and then down it would go without any help from the front teeth. A second set of jaws . . . who knew? Well, obviously somebody in Hollywood did!
Article also on online National Geographic.