The feeding apparatus of Chelus fimbriatus (Pleurodira; Chelidae) – adaptation perfected?

The feeding apparatus of the fringed turtle Chelus fimbriatus (Schneider, 1783) was studied to elucidate the feeding mechanics of an aquatic feeding specialist that has never been investigated in detail before, regarding gross morphology. The skull and hyoid apparatus as well as associated musculature were examined by computer tomography and dissection; the tongue was examined by scanning electron microscopy. The flat skull, the possibility to enormously depress the mandible combined with a cheek-like development, the large, ossified hyoid apparatus, and a well-distensible esophagus enable the turtle to produce an enormous suction force the prey is inhaled with. The jaw adductors are poorly developed in relation to other turtles and thus help keep the skull shape flat; nevertheless, they are able to generate high velocities and exhibit some new performance lines. The hyoid musculature is as well-developed as the hyoid apparatus itself, promoting the high depression velocity that is necessary for good feeding performance. The tongue is nearly reduced and lacks dorsal morphological differentiations. Taking all the morphological features into account, C. fimbriatus is an extremely well-adapted turtle making this species a very interesting object of investigation.