Project Details
Projekt
Amphibian sticky tongues: functional morphology, biomechanics, and evolution of a natural high performance adhesive system
Applicant
Dr. Thomas Kleinteich
Subject Area
Systematics and Morphology (Zoology)
Term
from 2013 to 2016
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 241240155
The transition from aquatic to terrestrial habitats during vertebrate evolution was related to numerous specializations for a life on land. While early tetrapods presumably fed on aquatic prey, the evolution of a tongue for prey capture and transport resulted in several new modes of terrestrial feeding. Within amphibians (i.e. frogs, salamanders, and caecilians), adhesive tongues that can stick to prey items and that will pull the prey into the mouth evolved several times. The use of adhesive tongues in amphibians ranges from protruding of the tongue over the tip of the jaw to ballistically firing the tongues at high speeds to remote targets. For a successful feeding event, the connection between the tongue and the surface of the prey items needs to be established within a few milliseconds and needs to be strong enough to lift the prey off the substrate. The actual cause of the adhesiveness of these tongues, however, remains obscure. It is likely that the combination of tongue shape, surface structure, and adhesive mucus is important for the tight connection between tongue and prey. The contributions of tongue surface properties, tongue anatomy, and mucus remain to be examined under consideration of the surfaces of the prey objects to which the tongues adhere. This project aims to reveal the structural principles and surface properties of amphibian tongues that underlie the tongue-prey interaction during the feeding strike in terrestrial amphibians. The state of the art imaging techniques micro computed tomography (µCT) and atomic force microscopy (AFM) will be applied in combination with light and electron microscopy (SEM and TEM) to systematically study the surface of amphibian tongues from the millimeter to the nanometer scale. Engineering approaches (indentation) will then be used to examine the surface and material properties of amphibian tongues. Information on the surface anatomy and characteristics of amphibian tongues will be complemented by high resolution three dimensional (3D) computer models. This anatomical and functional description of tongue surfaces and their properties will be combined with an experimental approach to quantify the performance of amphibian tongues on variable surfaces. For this, we will analyze high-speed video sequences that capture the feeding strike and we will measure the in vivo adhesive forces that act on the prey. By revealing the anatomy, the physical and chemical properties, and the performance attributes of amphibian tongues, this study will result in a comprehensive view of the tongue-prey interaction in amphibians - a natural high performance adhesive system.
DFG Programme
Research Grants
International Connection
Portugal, South Korea, USA
