Journal of the Marine Biological Association of the United Kingdom

Research Article

Rapid voluntary stomach eversion in a free-living shark

Juerg M.  Brunnschweiler a1c1, Paul L.R.  Andrews a2, Emily J.  Southall a3, Mark  Pickering a2 and David W.  Sims a3
a1 Institute of Zoology, Department of Ecology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
a2 Department of Basic Medical Sciences (Physiology), St George's Hospital Medical School, Cranmer Terrace, London, SW17 0RE, UK
a3 Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK

Article author query
brunnschweiler jm   [Medline] [Google Scholar
andrews pl   [Medline] [Google Scholar
southall ej   [Medline] [Google Scholar
pickering m   [Medline] [Google Scholar
sims dw   [Medline] [Google Scholar


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.

(Received May 24 2005)
(Accepted September 11 2005)

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