Some xanthid crabs are known to be toxic and have a serious threat of food poisoning.In present study,the distribution of toxicities in exoskeletal and visceral tissues in the xanthid crab, Zosimus aeneus collected from Ishigaki Island,Okinawa Prefecture,Japan and its paralytic shellfish poisoning toxins(PSP)profiles were examined.Toxicity assay showed that all of six individuals tissue were strongly toxic although there was significant difference among individuals in toxicity.Total toxicity of the individuals ranged between 37 500 MU and 116 000 MU,exceeding the estimated adult lethal dose of 5 000 MU.Generally,the toxicity of the exoskeletal tissues(909-1 610 MU/g)was higher than that of the visceral tissues(111-576 MU/g).The purification showed that the crude extract could be partly purified by repeat of chromatography on a Bio-Gel-P₂ column,and the specific toxicity of the toxin fractions rose approximately to 30 MU/mg from 4.8 MU/mg.Furthermore,the partial purified toxin fraction was applied to Bio-Rex 70 column chromatography,and the results showed that almost toxin was absorbed onto the resin,and approximately 9% of the toxin eluted by 0.03 mol/L acetic acid.This result indicates the toxin in Zosimus aeneus crab contained gonyatoxins(GTXs,a kind of paralytic shellfish poisoning toxins).HPLC analysis revealed that the GTXs fraction consisted of GTX2 and GTX3,along with decarbamoyl GTX2(dcGTX2)and decarbamoyl GTX3(dcGTX3)as the minor.