You know just in case your primary head gets crushed in the blast off or sustains an injury, it is always better to have a second head on standby! It sounds ridiculous but that is just one of the strange things that happen to a flatworm when taken into outer space.
Flatworms have long fascinated the scientific world of tissue regeneration due to their ability to grow back when cutting them in half. They can even survive if you cut off their head, they just grow it back. It seems though that the effects of outer space in terms of the lack of gravity have a confusing effect on the flatworm, as when injured they grow a second head! On Earth, no flatworm has ever grown a second head after amputation, but on the International Space Station in January 2015 it happened.
A group of flatworms was sent up via a resupply shuttle as scientist wanted to monitor if microgravity and changes in the geomagnetic field would have an impact on their cunning regenerative abilities. The study was started as it was a good opportunity to find out how cell activity varies in space. After five weeks they were brought back to Earth and compared to flatworms that had never left but had similar amputations. You may think flatworms and humans share nothing in common, however, these findings of how cells and microorganisms in flatworms react during space travel let scientist optimize space travel techniques making it safer for astronauts.
Another interesting consequence of their space travel seemed to be an apparent fear of water once they returned to Earth. Scientist reintroduced them to fresh spring water and the flatworms appeared to be in shock, curling up and paralyzed by the water. Researchers believe that this means the flatworms actually started going through a complete metabolism change during their time in space! Imagine if they had been left there longer, would they need water at all?
But the real fascination was, of course, the regeneration of two heads, an ability never seen before. Scientists also tested this change, they snipped off both heads and guess what? Yes, they just grew back!