Myxozoa are endoparasitic animals that exploit invertebrates and fish. Their phylogenetic position has long been controversial. However, recent placement within Cnidaria makes it clear that myxozoans have undergone astonishing morphological simplification associated with the evolution of parasitism. Such simplification is characteristic of many parasites but the genetic and developmental bases are poorly understood. Myxozoa demonstrate perhaps the most extreme example of simplification known to date, lacking a nervous system, gonads, cilia and centrioles. Differing degrees of simplification within the group provide an ideal opportunity to investigate the genetic and developmental bases of morphological simplification in a comparative approach. The myxozoan Buddenbrockia plumatellae forms muscular worms with a polarised body plan while the very closely related Tetracapsuloides bryosalmonae occurs as simple, unpolarised sacs. This fellowship proposes to generate transcriptomes of developmental stages from these two species by next-generation sequencing. Resulting data will be used to (i) compare developmental gene repertoires and expression levels of the two species and (ii) identify how myxozoans are related to other cnidarians. In a second step, expression patterns of developmental genes will be analysed by in situ hybridization. A third step will characterise the morphology and ultrastructure in regions of gene expression. Collectively, these investigations will provide a comprehensive picture of myxozoan development that can be compared to patterns in other myxozoans and free-living cnidarians. The research will (i) produce novel insights about morphological simplification associated with parasitism (ii) advance our understanding of a previously unrecognized radiation of endoparasitic cnidarians and (iii) provide training in cutting-edge techniques that will add to the candidate’s toolkit and career development.