Probable neurotoxin. May act as a ion channel modulator that causes the immobilization of prey. This primitively aquatic arthropod may feed on crustaceans (or other arthropods), since its venom contains many chitinases. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. The transcriptomic profile of the venom glands of S.tulumensis shows that the injected cocktail of toxins is dominated by enzymes (mostly proteases S1 and chitiniases) and that it includes this probable paralytic neurotoxin.