Toxin that is lethal to crab. It interacts with divalent metal ions (zinc and nickel) suggesting it may function as a metal ion chelator to regulate metal ion levels or as a metal ion transporter, or that its function is modulated by metal ions. Is not active against any of the voltage-gated potassium and sodium channels tested. In addition, it does not show activity in bacterial and fungal growth inhibitory assays as well as in hemolytic assays. Expressed by acrorhagi. Has the structural arrangement of two alpha-helices stabilized by disulfide bonds (CSalpha/alpha 4(S-S)). This toxin interacts with divalent metal ions (zinc and nickel). This suggests it may function as a metal ion chelator to regulate metal ion levels or as a metal ion transporter, or that its function is modulated by metal ions. Both Thr-23-Pro-24 and Cys-71-Pro-72 are in the trans conformation. Belongs to the Acrorhagin I family.