Aglajids are slug-like gastropods with an internal reduced shell and with few exceptions lacking a radula. They occur across temperate and tropical latitudes and are mostly associated with soft bottoms. The monophyly of the various genera of the family is disputed and there are still many open questions about the relationship in the group. These projects will clarify the systematics of the family and will contribute to better understanding the patterns of biogeography and speciation in the marine realm.