The xanhid crab Atergatis floridus and the blue-lined octopus Hapalochlaena cf. fasciata have long been known as TTX-bearing organisms. It has been speculated that the TTX possessed by both organisms is exogenously toxic through the food chain, since they are reported to have geographic and individual differences. The source and supply chain of TTX for both of these organisms, however, remain unclear. On the other hand, since crabs are one of the preferred prey of octopuses, we focused our attention on the relationship between the two species living in the same site. The aim of this study was to determine TTX concentrations and TTX profiles of A. floridus and H. cf. fasciata, collected simultaneously in the same site, and examine the relationship between them. Although there were individual differences in the TTX concentration in both A. floridus and H. cf. fasciata, the toxin components commonly contained 11-norTTX-6(S)-ol in addition to TTX as the major components, with 4-epiTTX, 11-deoxyTTX, and 4,9-anhydroTTX as the minor components. The results suggest that octopuses and crabs in this site acquire TTX from common prey, including TTX-producing bacteria and/or may have a predator-prey relationship.
Keywords: blue-lined octopus; tetrodotoxin; tetrodotoxin analogs; xanthid crab.