NASA plans to establish a base on the Moon in the next decade, after which astronauts are expected to fly to Mars and establish the first outpost there. To make it easier for people to get used to a new place, a whole ecosystem will be needed, which should also include animals, but which ones?

David Catling, an astrobiologist at the University of Washington in Seattle, believes that living ecosystems on the Moon and Mars are still the stuff of science fiction, not the subject of scientific investigation. With all this said, there is speculation as to which animals might have been the first to populate the Moon and Mars bases.

NASA planetary scientist Christopher McKay stated that the main problem for pets will be the force of gravity. The gravitational force on the Moon is 1/6 of that of the Earth and 1/3 on Mars. Therefore, low gravity can negatively affect the growth of muscles and bones, and therefore animals will not be able to stand and walk normally.

Accordingly, small animals are best suited to live on Mars or the Moon: for example, mice, deep-sea inhabitants (crustaceans and fish) and insects.