In 2003, researchers found freshwater snails had mated in space; their gravity-sensing statoconia were 50% larger by volume than matched ground controls

Experiments conducted aboard the Space Shuttle demonstrated that pond snails bred in microgravity possessed larger gravity-sensing structures known as statoconia compared to their Earth-reared counterparts. Additionally, swordtail fish embryos showed an increase in otolith size during their development in orbit. Conversely, juvenile fish with pre-formed structures exhibited little change. This research underscores the essential influence of gravity on the development of balance structures in aquatic species.