Takeshi Yasumoto

Occurrence of toxic crabs in Ryukyu and Amami Islands

Two typical cases of illness associated with the ingestion of toxic crabs are described. The signs were characterized by vomiting, paralysis, and rapid death. In the screening test for toxic crabs, two species, Zosimus aeneus and Platypodia granulosa, were found to contain a paralytic toxin showing a dose-death time curve similar to that of tetrodotoxin. In both species the toxin was found to be present mostly in the exoskeleton and muscle of appendages and only slightly in the cephalothorax. A marked individual variation of toxicity was also recognized. The toxin was easily dialyzable, soluble in water and methanol, and insoluble in most fat solvents.