Within its diverse collection about 23 groups of multicellular animals (Metazoa) are represented, with currently more than 31.000 catalogue entries. There are three main parts of international rank. First, among the Oligochaeta there are 4.200 catalogue entries, with 1.346 types, including the historical collection in particular of Hamburg’s long time curator and oligochaet specialist Wilhelm Michaelsen (1887-1923), who was working from 1887 to 1923. Thus, of the c. 8.000 species of Oligochaeta known worldwide, 16% of all named taxa are represented by type material in the CeNak, i.e. every fifth oligochaet in the world is represented in Hamburg by it name-bearing specimens. Second, about 3.700 catalogue entries of Tunicata are present, with 1.343 entries for the Ascidia (with 309 types). Third, there are 1.538 series of Bryozoa with 54 types known. Other parts comprise Echinodermata with 3.900 series and 209 types, Cnidaria (3.260 lots, 156 types), Porifera (1.988 series, 215 types), Hirudinea (979 series, 35 types) and Chaetognatha with 700 series. More than 25.000 entries are currently digitally registered, using FileMaker Pro.