title: A fish that uses its hydrodynamic tongue to feed on land.
abstract: To capture and swallow food on land, a sticky tongue supported by the hyoid and gill arch skeleton has evolved in land vertebrates from aquatic ancestors that used mouth-cavity-expanding actions of the hyoid to suck food into the mouth. However, the evolutionary pathway bridging this drastic shift in feeding mechanism and associated hyoid motions remains unknown. Modern fish that feed on land may help to unravel the physical constraints and biomechanical solutions that led to terrestrialization of fish-feeding systems. Here, we show that the mudskipper emerges onto land with its mouth cavity filled with water, which it uses as a protruding and retracting 'hydrodynamic tongue' during the initial capture and subsequent intra-oral transport of food. Our analyses link this hydrodynamic action of the intra-oral water to a sequence of compressive and expansive cranial motions that diverge from the general pattern known for suction feeding in fishes. However, the hyoid motion pattern showed a remarkable resemblance to newts during tongue prehension. Consequently, although alternative scenarios cannot be excluded, hydrodynamic tongue usage may be a transitional step onto which the evolution of adhesive mucosa and intrinsic lingual muscles can be added to gain further independence from water for terrestrial foraging.
authors: Department of Biology, Universiteit Antwerpen, Antwerp 2610, Belgium krijn.michel@uantwerpen.be.
authors: Krijn B
authors: KB
authors: Michel
authors: Department of Biology, Universiteit Antwerpen, Antwerp 2610, Belgium Institute of Systematic Zoology and Evolutionary Biology, Friedrich-Schiller-University Jena, Jena 07743, Germany.
authors: Egon
authors: E
authors: Heiss
authors: Department of Biology, Universiteit Antwerpen, Antwerp 2610, Belgium Department of Movement and Sports Sciences, Ghent University, Ghent 9000, Belgium.
authors: Peter
authors: P
authors: Aerts
authors: Department of Biology, Universiteit Antwerpen, Antwerp 2610, Belgium Evolutionary Morphology of Vertebrates, Ghent University, Ghent 9000, Belgium.
authors: Sam
authors: S
authors: Van Wassenbergh
mesh_terms: D000818:Animals; D005075:Biological Evolution; D057446:Hydrodynamics; D010473:Perciformes / Q000502:physiology*; D011235:Predatory Behavior; D012455:Salamandridae / Q000502:physiology*; D014059:Tongue / Q000502:physiology*
keywords: hyoid; kinematics; mudskipper; newt; prey capture; tongue