If humans were ever able to live in space, how would children born there react to changes in gravity?<\/p>\n
That\u2019s 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 \u2013 thousands of them.<\/p>\n
In 1991, almost 2,500 jellyfish polyps (a jellyfish in an early life stage) were sent to space aboard the Columbia shuttle.<\/p>\n
While these gelatinous marine animals don\u2019t seem particularly similar to humans, we do have one thing in common: we can sense which way is up using gravity.<\/p>\n
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).<\/p>\n
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.<\/p>\n
The hairs sense this and send signals to neurons. Using this system, jellyfish can tell whether they\u2019re swimming up or down.<\/p>\n
Humans have calcium carbonate structures in our inner ears that cause sensitive hair cells to move. This allows our brains to register gravity.<\/p>\n
So, the researchers wanted to test that whether jellyfish raised in space still developed their gravity-enabled system \u2013 as humans raised in microgravity might have similar results.<\/p>\n
A gravity-sensing system<\/p>\n
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.<\/p>\n