The tropical barnacle, Balanus amphitrite, is an economically important fouling species (it settles on natural and artificial submerged surfaces) with a short generation time and larvae that are relatively easy to culture in the laboratory. These attributes have contributed to its acceptance as a model species for larval settlement studies. The settlement stage larva - the cyprid- typically displays searching behavior, in which the cyprid ‘walks’ over the surface using the attachment discs of its paired antennules. This behavior has proved difficult to measure in detail by conventional means. However, EthoVision is able to measure this behavior in detail. The three phases of cyprid exploratory behavior - wide search, close search and inspection - could be extracted from EthoVision data. Furthermore, valuable information was gathered on how larval behavior changes according to cyprid age or upon exposure to a cue. EthoVision allows to assay compounds and natural biofilms (bacteria and macroalgal spores) for antifouling activity. The studies reveals that the application of automated video tracking is a new approach to study marine larval settlement and is likely to find wide application in both fundamental and applied studies of this important life-cycle process.

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