All The Better To Eat You With My Dear!

Evolution 2009

The evolution of parrotfish saw two morphological innovations, pharyngeal jaw modification and the novel intramandibular joint. The pharyngeal jaw, a characteristic of all parrotfish, is basically a second set of jaws in addition to the primary jaw. Kind of like a mouth in a mouth.  Didn’t the creature from Alien have a pharyngeal jaw?  In contrast, not all parrotfish possess the intramandibular joint, a “unique jaw linkage [that allows] for increased control of the lower jaw” and allows for a larger mouth gape. Both of these modifications are presumed to be adaptive to allow for better scraping of algae off corals. In the evolution of the parrot fishes the pharyngeal jaw came first and was followed by the intramandibular joint.

Samantha Price presented today on research testing the extent that these morphological innovations potentially created new niche space and thereby increased diversification, i.e. the proliferation of new species.    Prices examined several different morphological metrics as a measure key aspects of this diversification, e.g. gape size, protrusion, body size, and the very sophisticated sounding jaw kinematic transmission.  Overall, her results are both intriguing and complex.  The evolution of the pharyngeal jaw was not matched by significantly faster rates diversification in of the morphological metrics. Indeed some appeared to actually slow down.    However, with the intramandibular joint came increased diversification, i.e. an adaptive radiation.

Dr. M (1636 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.





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4 comments on “All The Better To Eat You With My Dear!
  1. This is absolutely fascinating. I had no idea that creatures other than morays possessed pharyngeal jaws.

  2. Probably, the best known feeding apparatus among teleostan is the feeding apparatus of the cichlids. In terms of species richness, cichlids exceed labrids whereas labrid morphological diversity
    is comparable to that of the cichlids in terms of feeding
    modes, as represented by the wide variety of their skull
    forms. The radiations of the cichlid and labrid fishes is
    widely believed to result from the “key innovation” of a
    unique pharyngeal jaw apparatus. Has Samantha Price introduced some comparison between cichlids and parrotfish?

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