The unusual oral morphology of deep sea dragonfishes (also known as loosejaws) allow them to open and snap their mouths shut at high speeds, according to a study to be published in a forthcoming issue of the Biological Journal of the Linnean Society.
Deep-sea fishes of the family Stomiidae are best known for their long, fang-filled jaws and huge mouths without a floor that allow them to consume prey more than half their size.
By studying computational models of the jaws of the dragonfishes, Christopher Kenaly found that the absence of connective tissue between the left and right halves of the lower jaw (the floor of the mouth) allows the dragonfishes to close their mouths at high speeds due to the low drag incurred.
Additionally, lacking the floor of the mouth also enables the dragonfishes to use a smaller muscle mass to close the jaws at high speed, allowing the fishes to invest less energy in their jaw mechanism.
For more information, see the paper: Kenaly, CP (2012) Exploring feeding behaviour in deep-sea dragonfishes (Teleostei: Stomiidae): jaw biomechanics and functional significance of a loosejaw. Biological Journal of the Linnean Society, doi:10.1111/j.1095-8312.2012.01854.x
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