Written Paper

Rapid voluntary stomach eversion in a free-living shark  [2005]

Brunnschweiler, J.M. Andrews, P.L.R. Southall, E.J. Pickering, M. et al.

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Video observation of oral gastric eversion in a free-living Caribbean reef shark (Carcharhinus perezi) shows voluntary gastric eversion followed by retraction not only occurs, but is extremely rapid (lasting [similar]0.3 s). Eversion may occur by stomach relaxation–oesophageal contraction coupled with increased abdominal pressures to enable prolapse, and retraction by a mechanism analogous to suction feeding. This behaviour provides a ‘cleansing’ function for removing indigestible food particles, parasites or mucus from the stomach lining. Sharks, and possibly other animals with similar gut morphologies, may use this technique to help maintain a healthy alimentary tract.