Tube-building and feeding behaviour of Neoamphitrite robusta shared similar initial activities of tentacle extension, particle gathering, and passage of particles to the oral region. Particles were sorted by the inner lips, but the extent of sorting depended upon whether the animal was tube-building or feeding. Particles to be incorporated into the tube were passed over the outer lips and moulded into the tube in a stereotyped manner. Tube-rebuilding in test specimens (tubes removed) proceeded significantly faster than tube-building in control specimens (within tubes), although feeding was significantly less in the test specimens. Nonfeeding specimens were able to construct tubes. The two behaviours were able to proceed independently, although feeding supplemented tube-building with the passage of rejected particles to the tube.