Tube-dwelling has been recognized PreViOuSlY as a life-style for several meiobenthic species, but behavioural observation of living specimens has rarely been reported. The extent to which tubebuilding and tube-dwelling occurs within meiofaUna, and how they have influenced evolutionary and ecological processes as well as morphology within these oymisnis. is relatively unknown but potentially of great significance. In addition to direct obse.wation of tube-building and the occurence of tubes in natural habitats, the internal anatomy associated with tube-building in two nematode species (Ptycholaimellus jacobi, P. ponticus) and one harpacticoid copepod species (Stenheliapalustris) is the focus of this study. Special attention is given to the Secretory products, glands, and their association with secretory pores. Also, the role of meiobenthic tube-dwelling activities in relationship to their environment is extensive discussed.