Trip to space seems to have spurred a flatworm to regenerate a second head
It may sound like something out of a 1950’s science fiction story, but spending time in space has apparently spurred a flatworm into growing two heads. Flatworms are actually known for their regenerative abilities, and this particular worm was actually cut in half before heading into orbit on the International Space Station (ISS) in the hope that it would regrow its body. However, regenerating with a second head, along with a number of other abnormal developments, isn’t exactly what scientists were expecting when designing the experiment. The second head doesn’t mean we need to fear radioactive space monsters from outer space, but it does raise concerns over long-term health effects of living away from the Earth.
Altered in orbit
Planarian flatworm (Dugesia japonica) regeneration is usually much more predictable. The tiny creatures regularly handle fission without a problem, and can use it to boost populations. A single worm splits in half, and each half regrows whatever pieces are missing. So usually a tail will regrow a head, and a head will regrow a tail. Researchers have known that a two-headed variation was technically possible, but the Tufts University researchers had never encountered a two-headed worm before, even after 18 years of research. What’s more, the underlying change must have been substantial, as that two-headed flatworm returned from space only to continue making two-headed copies of itself.
The other flatworms have also exhibited changes to their physiology and behavior, although they’re understandably less dramatic than growing a second head. They exhibited an reaction to fresh water when first returning home, becoming temporarily paralyzed when first immersed. They also don’t show flatworms’ normal aversion to light, and will not seek out darker portions of their containers when given the chance.
Changes from flying and floating
It’s not clear what is driving these various changes. A change in the worms’ microbiomes may help explain the temporary reaction to fresh water, and other research has already shown that bacteria notice when they’re in microgravity too. Other influences include a diminished pull from the planet’s geomagnetic field, stress from takeoff and landing, or just issues related to floating in microgravity while on board the space station.
At this point, scientists have a good understanding of what chemical changes could change a flatworm, since those things can all be tested here on the ground. Isolating what are likely mechanical influences from traveling to and in space are a new frontier, but they need to be understood if humans hope to export our lifestyles to other planets. Nobody believes that astronauts will sprout second heads after being in space, but animals like flatworms are still a good way to study the importance of gravity on living systems, partially thanks to their dramatic reactions to that environment.
Source: Flatworm Travels to Space With One Head, Comes Back With Two by Nathaniel Scharping, D-brief