Chemical languages in larval settlement of marine organisms - Settlement inhibiting substances against barnacles, and settlement inducing substances in ascidians

For understanding the interactions between marine organisms, me focused on larval settlement (attachment and metamorphosis) of sessile marine organisms, where chemical substances (chemical signals) play important roles. Here we report firstly the settlement inhibiting substances against barnacles (Balanus amphitrite). More than 300 marine invertebrates were screened for antifouling activity, and more than 60 antifouling compounds including almost 30 new ones were obtained. Some of these compounds [especially with isocyanide, isothiocyanate, and/or formamide group(s)] show strong antifouling activity without toxicity at the very low concentrations. Secondly, we report the metamorphosis inducing substances for ascidians (mainly Halocynthia roretzi). Almost 40 compounds which induce/promote larval metamorphosis were obtained from marine organisms. The real cue for metamorphosis has been isolated from conspecific conditioned water and identified as lumichrome.