Feeding Mechanism of Testudo Hermanni Boettgeri (Chelonia, Cryptodira)

Abstract

Feeding of Testudo hermanni boettgeri was studied by film analysis and anatomical examination of the musculature and skeleton elements involved. Film sequences were analysed to describe the movements of food item, neck, jaws, and tongue. The feeding cycle is divided into food uptake (ingestion), followed by several transport and manipulation cycles (intraoral transport), and finally swallowing of the food (deglutition). The results show that in Testudo hermanni boettgeri the tongue is the main tool for food uptake and intraoral manipulation. The hyoid apparatus supports the floor of the mouth and is adapted to the highly movable tongue. Compared to aquatic species the hyoid is smaller, more flexible, and less ossified. Skull shape and arrangement of jaw muscles also demonstrate adaptation to terrestrial life. The jaw muscles are less developed, their insertion areas are smaller and do not extend as much caudally as in aquatic species. The organisation of the feeding mechanism in tetrapods depends on biophysical constraints imposed by the surrounding medium. In this organisation the hyolingual complex plays an important role. The tongue of terrestrial turtles tends to be larger, more muscular, more mobile, and tends to have a more complex surface than in aquatic forms. The feeding mechanism of Testudo hermanni boettgeri shows the typical situation of a turtle that is fully adjusted to terrestrial life.