The World Register of Marine Species (WoRMS) celebrated its 10th anniversary in 2017. Over thepast ten years, the content of WoRMS has grown steadily, currently containing more than 242,000accepted marine species names. WoRMS is therefore unique: there is no comparable globaldatabase for marine species, which is driven by a large, global expert community, supported by aData Management Team and can rely on a permanent host institute, dedicated to keeping WoRMSonline. The system has seen several user applications, including facilitating local and regionalmarine species data management and data analysis, but also answering big scientific questions forexample about the estimated number exiting marine species, providing a metric for how much wedo and do not know about life in the oceans.One of the unique features of WoRMS is that it is containing and integrating over 100 global, 12regional and 4 thematic species databases integrated within a common taxonomy. This allowsregional, thematic or ecological expert groups to focus on specific contents of the database,providing additional information and creating community ownership of a specific subcomponentof WoRMS.A regional example of WoRMS is BeRMS, the Belgian Register of Marine Species. Published in 2010,this register enabled to provide an inventory of all marine species encountered within the BelgianExclusive Economic Zone, including the intertidal zone.Now, a major update of the Belgian Census has started. A major literature review, dataminingactivities of marine biogeographic databases such as the European Biogeographic InformationSystem (EurOBIS) and additional species surveys are planned in order to complete this register,allowing to provide a nearly complete assessment of the Belgian marine biodiversity.