An enclosed ecosystem which is stable on Earth will behave differently when brought into space. Micro-gravity and radiation will affect the dynamics of material circulation or the activities of small creatures of the ecosystem. One series of space experiments aiming to address such issues was planned in the United States (It is termed as ABS--Autonomous Biological System) and Japanese group has been involved with cooperating with the analysis of the flight samples. Before the ecosystem will be on board Russian Space Station "Mir" later 1996 for 3 months, a preliminary flight was carried out in May 1996 on Space Shuttle (STS-77) for 10 days flight. It was the first of such experiments to fly one whole ecosystem in space.