Calitoxin, also known as CLX, is a sea anemone neurotoxin produced by the sea anemone Calliactis parasitica. It targets crabs and octopuses, among other invertebrates. Two isoforms (CLX-1 and CLX-2) have been identified, both of which are formed from precursors stored in the stinging cells of the anemone. Once the toxin is activated and released, it causes paralysis by increasing neurotransmitter release at invertebrate neuromuscular junctions. Along with several other toxins derived from anemones, CLX is useful in ion channel research. Certain structural aspects of calitoxin are dissimilar from sea anemone toxins that also target the sodium ion channels. Other toxins resembling calitoxin function in completely different ways.