The Bdelloidea are free-living, predatory mites with a cosmopolitan distribution, inhabiting practically all temperate zones. They inhabit the top soil layer, most vegetation strata and the marine littoral zone. The CunaxidBase was compiled by Dr. Jacob den Heyer (custodian), consisting of 329 species and 4 synonyms. The BdellidBase, consisting of 246 valid species and 66 synonyms, was compiled by Drs Jacob den Heyer and F.A. Hernandes (custodian). The BdelloideaBase substitutes for the CunaxidBase of the 2011 Annual Checklist.