Jean VACELET is specialist of marine Mediterranean sponges (Porifera). His main interests in biology and ecology of this phylum are phylogeny, reproduction, cytology, skeletogenesis, symbiosis with micro-organisms, research of bioactive molecules and chemotaxonomy. He is a sponge taxonomist world recognized and participated to the description of a lot of new taxa and of the phenomenon of carnivory in a deep-sea sponge. He is also a diver often visiting coralligenous. In 1991 he has been honored with the Prince Albert 1st medal and is Doctor Honoris Causa of the University of Ancona (Italy) since 2001.