Back in the early ’90s, NASA determined that newborn jellyfish nurtured in space are probably not fit for life back on Earth. What does that mean for us?
Jellyfish, foreign to us in so many ways, are like humans in one very particular manner: They orient themselves according to gravity. As the biologist RR Helm explains it:
When a jelly grows, it forms calcium sulfate crystals at the margin of its bell. These crystals are surrounded by a little cell pocket, coated in specialized hairs, and these pockets are equally spaced around the bell. When jellies turn, the crystals roll down with gravity to the bottom of the pocket, moving the cell hairs, which in turn send signals to neurons. In this way, jellies are able to sense up and down. All they need is gravity.
Humans, of course, are similarly sensitive. We sense both gravity and and acceleration using otoliths, calcium crystals in our inner ears that move ultra-sensitive hair cells, thus informing our brains which way gravity is pulling us. So if the space-raised jellyfish didn’t fully develop their version of gravity-sensors, the thinking goes, it’s likely that humans raised in microgravity would have similar trouble.
(Photo by Flickr user Croswald9)