All three sub-taxa of the Rotifera (Seisonidea, Monogononta and Bdelloidea) are characterised by a pharyngeal gizzard (mastax) with cuticular hard elements (trophi). The trophi reach sizes of 15 to 50 μm and are used to crush food and, in predatory species, to grasp prey.

The hard elements can be moved relative to each other and within the mastax by muscles inserted into the trophi and push the food towards the caudally adjacent oesophagus.

The aim of the project is the comparative study of the structure and function of the seven different mastax types of Rotifera. This includes analysing the structure and morphology of the trophi as well as a detailed study of the muscle and gland system of the gizzard.

The findings of the study will be evaluated against the background of the currently discussed relationships and the evolution of the mastax will be traced.