Capsule recoil after nematocyst discharge and sequence elements in Cnidoin primary structure. (A) capsule size change during discharge of a stenotele. (B) domain organisation of Cnidoin and Minicollagen-1 (NCol-1) and alignment of respective CRD domains. Conserved cysteines are highlighted. (C) alignment of the elastic domain of Cnidoin with a homologous sequence in Spidroin-2. Highlighted is the GxGQQ motif present in both sequences.