Transposable elements have been shown to play a role in genome evolution and contribute to genome size expansion. The Scyphozoan jellyfish Aurelia genus is comprised of a number of species, including Aurelia aurita, and Aurelia coerulia (previously Aurelia sp.1). Interestingly, the genome of A. coerulia is almost twice as big as that of A. aurita. In this study, we investigate whether this genome size difference is due to expansion of certain transposable elements.