A Zanclus cornutus (Moorish idol), with distinctive yellow and black stripes, shown underwater in a reef — A new study using high-speed video shows for the first time that the reef fish Zanclus cornutus (Moorish idol) and the related surgeonfish can move their jawbones sideways as well as up and down. This ability is very uncommon among vertebrate animals and may have helped these fish become dominant herbivores on reefs. (Photo of Zanclus by Getty Images)

How Are They Biting?

High Speed Video Reveals Unexpected Jaw Movements in Reef Fish

by Andy Fell
May 06, 2025

Some reef fish have the unexpected ability to move their jaws from side to side, biologists at the University of California, Davis have discovered. This ability – which is rare among vertebrate animals – allows these fish to feed rapidly and efficiently on algae growing on rocks. The work is published May 5 in Proceedings of the National Academy of Sciences.

Being able to move your jaw from side to side might not seem surprising from a human point of view, but if you look across all vertebrate species – half of which are fish – it is almost unique, said Peter Wainwright, professor in the Department of Evolution and Ecology at UC Davis and senior author on the paper.