John's research group at the MBA focuses on the ecology, reproduction and development of ‘sessile’ animals—those that, as adults, live permanently attached to a solid surface. Familiar examples include barnacles, corals and oysters, although sea-squirts and sea-mats have been the main focus of our research. This stationary lifestyle is made possible by the supply of food in the form of plankton and other particles drifting in the surrounding water. A strand of this research concerns how these forms still manage to mate, despite not being able to approach each other. The key is often male gametes that disperse in the water and are collected by members of the same species, generally as an adjunct to filter feeding. An additional research concern is non-native species in these sessile faunas, and the mechanisms by which non-natives spread along coastlines. This has involved surveys, monitoring and experimental investigations using retrievable settlement panels, and often requires detailed morphological examination backed by DNA sequence information to distinguish similar species. Non-native marine species can have serious adverse effects on economic activities and on native species. Our investigations are intended to inform management of human activities to minimize future introductions, and to assist horizon-scanning exercises to focus efforts on excluding the most serious threat species.