mates. Much better to stick where they are and resist the current's pull. Sticking is what a lot of sea creatures do extremely well, as anyone who has had to scrub a boat hull well knows. Hard, smooth surfaces are at a premium in the sea, and it doesn't take long before submerged structures are covered with a slimy coat of bacteria and algae.

Fouling, as this growth is called, not only increases drag on moving vessels but clogs industrial pipelines and speeds corrosion on metal surfaces. Pioneering colonies of microbes pave the way for later settlement by invertebrate larvae and seaweed spores, building up to "hard fouling" by barnacles, muscles, anemones, and other organisms that eventually demand costly removal.

It's not only undersea where aquatic microbes like to grow on reefs and sunken ships. Microbes can attach to any exposed site in contact with watery fluids, causing problems in places such as heat exchangers, trickling filters, or aquaculture circulation systems, and even in human medical implants and prosthetic devices. Since it's not possible to use toxic chemicals to deter squatters from these places, nor easy to remove them by scrubbing, scientists must look for more ingenious ways to avoid fouling.

New answers might come from studies of how marine organisms attach themselves, and of how large aquatic animals and plants prevent their surfaces from being settled on. Researchers have already investigated the genetic coding for biological adhesives used by other organisms, such as nitrogen-fixing bacteria that glue themselves to the root nodules of leguminous crops. Disease-causing bacteria that adhere to mucous membranes in the nose, throat, and lungs also use biological adhesives. Knowing which genes allow marine bacteria to produce their "glue," and analyzing which cues in the