The Baltic Sea is highly affected by eutrophication, but more knowledge is needed regarding how this influences many of the organisms that live there. One understudied species is the moss animal Einhornia crustulenta. In this study, steps are taken towards better understanding the ecology of E. crustulenta and how it might be influenced by eutrophication. This was done by two experiments. In the first experiment, it was tested whether E. crustulenta can feed on some phytoplankton species connected to eutrophication in the Baltic Sea (including e.g. the filamentous cyanobacteria Nodularia spumigena and Aphanizomenon flos-aquae and the flagellate Prymnesium parvum). In the other experiment, it was tested whether the snail Theodoxus fluviatilis and the isopod Idothea baltica are potential predators on E. crustulenta in the Baltic Sea. The results show that E. crustulenta are able to feed on e.g. N. spumigena and P. parvum and thus might be benefitted by eutrophication. Furthermore, the results show that neither T. fluviatilis nor I. baltica seem to feed on E. crustulenta. The results from both studies imply that E. crustulenta might benefit from eutrophication in the Baltic Sea and expand without control from predators. Here, some steps have been taken towards better understanding the ecology of E. crustulenta, but further research is needed. Future studies could include more potential predators and also study earlier life stages of E. crustulenta.