If humans were ever able to live in space, how would children born there react to changes in gravity?
That’s a question space agency NASA wanted to answer in the 1990s. A team, led by Dorothy Spangenberg, devised an experiment that could emulate this. And it involved jellyfish – thousands of them.
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In 1991, almost 2,500 jellyfish polyps (a jellyfish in an early life stage) were sent to space aboard the Columbia shuttle.
While these gelatinous marine animals don’t seem particularly similar to humans, we do have one thing in common: we can sense which way is up using gravity.
When a jellyfish polyp grows into its medusa phase (the life stage with which we are most familiar), it forms calcium sulphate crystals on its main body (known as its bell).
These crystals are surrounded by a cell pocket that is coated in specialised hairs. When jellyfish turn in the water, the crystals roll in the same direction thanks to gravity.
The hairs sense this and send signals to neurons. Using this system, jellyfish can tell whether they’re swimming up or down.
Humans have calcium carbonate structures in our inner ears that cause sensitive hair cells to move. This allows our brains to register gravity.
So, the researchers wanted to test that whether jellyfish raised in space still developed their gravity-enabled system – as humans raised in microgravity might have similar results.
A gravity-sensing system
The jellyfish polyps were sent into space in bags of artificial seawater, with accompanying researchers on board tasked with accelerating their growth. The experiment lasted around nine days, and around 60,000 jellyfish had developed.
Once back on Earth, the researchers discovered that the jellyfish struggled to swim, in contrast to the control group on Earth. The space jellies demonstrated ‘pulsing abnormalities’, with the scientists concluding that the jellyfish had a severe case of vertigo.
So while the animals still developed calcium sulphate crystals in space, the jellyfish struggled to adjust to life on Earth – suggesting that humans born in space may also act in a similar way.
Top image: a jellyfish in its medusa stage. Credit: Michael Shmelev/500px/Getty Images
