 Currently, 13 different hainantoxins are known (HNTX-I – HNTX-XIII), but only HNTX-I, -II, -III, -IV and -V have been investigated in detail.HNTX-I, HNTX-III, HNTX-IV and HNTX-V are made by the Chinese bird spider "Haplopelma hainanum" (="Ornithoctonus hainana", "Selenocosmia hainana").Hainantoxins I, III, IV and V show high homology, including the presence of three disulfide bonds that form an inhibitor cysteine knot (ICK) motif.