抄録
Soil or terrestrial ciliates live in the water which may either cover the surfaces of litter as a thin film or fill the pores of soils. These ciliates, which may adapt to various environments from dry to wet depending on the weather, share some important roles in the natural ecosystems. Nevertheless, only a little knowledge has been available on their taxonomy and ecology. This is mainly due to the difficulty in identifying ciliate species, and to the lack of appropriate methods for detecting soil ciliates and for estimating their biomass. This review presents a list of ciliate species in straws of rice-stubbles and in soils from drained paddy fields which are considered one of the terrestrial habitats. A total of 79 species belonging 12 orders were found in the straws and soils. The number of hypotrich species (37 species; 46.8%) was remarkably greater than that of other taxa. These ciliates successively emerged as free-swimming forms when straws or soils were placed in the petri dishes containing tap water. A common adaptive trait of these ciliates may be their ability to produce resting cysts. The tests of drought resistance indicated that more than half of them remained viable in a desiccated state for 18 days. Finally, a brief discussion was made on some problems to be resolved in soil ciliate ecology.
