Closed ecological system

If the purpose is to maintain a life form, such as a mouse or a human, waste products such as carbon dioxide, feces and urine must eventually be converted into oxygen, food, and water.

While both chemotrophic and phototrophic organisms are plausible, almost all closed ecological systems to date are based on an autotroph such as green algae.

[2][3] Man-made closed ecological systems which were created to sustain human life include Biosphere 2, MELiSSA, and the BIOS-1, BIOS-2, and BIOS-3 projects.

[4] Bottle gardens and aquarium ecospheres are partially or fully enclosed glass containers that are self-sustaining closed ecosystems that can be made or purchased.

They can include tiny shrimp, algae, gravel, decorative shells, and Gorgonia.