The results of surveys made of the invertebrate fauna of the Krakatau Islands in the 1980s, about 100 years since Krakatau’s destructive eruption, are reviewed in the context of earlier surveys, and as a reference for future work on the islands as colonization continues. The possibility of invertebrates surviving the 1883 eruption is discussed and, on balance, rejected. Dispersal modes of invertebrate groups are related to their archipelagic distributions; prerequisites for successful establishment and the sequence of colonization are discussed. The present fauna of the young island of Anak Krakatau (emerged 1930) is discussed in relation to records of recolonization of the three older islands in the first fifty years after 1883. We identify three early pioneer animal communities that exploit energy sources outside the island system and thus are able to establish themselves before plants have successfully colonized. Invertebrate groups are at differing stages on the route towards an equilibrium number of species, and ecological changes involved in equilibration of the fauna as a whole should be the subject of future studies.