Cited research: Proc. Natl Acad. Sci. USA doi:10.1073/pnas.1000668107 (2010)

Aquatic bacteria can access new environments by zipping around on larger organisms.

Hans-Peter Grossart of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries in Stechlin, Germany, and his colleagues labelled three species of bacterium with a fluorescent protein. They then tracked the microbes' movements in laboratory water columns with and without the water flea Daphnia magna, which usually travels up and down the water column each day. When water fleas migrated towards a light, the bacteria moved along with them, either by attaching to the surface of their bodies, or by being ingested and defecated by the water fleas.

Similar behaviour was observed in a German lake, suggesting that bacteria hitchhike on zooplankton in natural settings as well — a phenomenon that could influence aquatic ecology. H.L.