Jellyfish were sent into space as part of a scientific experiment.
Space Life Science-1 (SLS-1) Mission
The jellyfish, part of an experiment led by Dorothy Spangenberg, were launched into space on the rocket STS-40 during the Space Life Science-1 (SLS-1) mission on June 5th, 1991. The mission lasted for nine days. The purpose was to study the effects of microgravity on jellyfish development.