Jellyfish joined the list of animal astronauts in the early ‘90s. However, once safely back on Earth, Aurelia aurita found it difficult to get used to the planet’s gravitational pull. Scientists are hoping to use this information to determine whether longer space travel would have any unfavourable effects on humans.
In 1991, the space shuttle Columbia carried 2,478 tiny, baby jellyfish called polyps into space to test how microgravity would affect their development. During the nine-day mission, the polyps grew into the next life stage, called ephyrae, which could swim and pulse around tiny vials of seawater. As cool as being an astronaut baby might sound, the jellies didn’t develop the same gravity-sensing capabilities as their Earthly relatives.
Jellyfish have special structures called gravity receptors, which help them swim and tell up from down. These receptors have tiny crystals of calcium sulphate called statoliths that ring the bottom edge of their mushroom-like bodies. The crystals are stored in little pockets lined with hair cells, and when the jellyfish moves, the crystals roll around, signalling to the brain which way is up by triggering those hair cells. Although the pockets seemed to develop normally in space, once back on Earth the jellies had difficulty figuring out how to swim around in normal gravity.
Humans have very few things in common with jellyfish—and one of them is their gravity sensing system. This is why it’s especially important to know whether statolith crystals form in space, since humans have similar calcium-containing crystals (otoconia) in their inner ears, helping us mantain the balance. This means that if jellyfish had trouble developing their gravity senses in space, it’s likely human space babies wouldn’t be much better off.
This isn’t putting off some brave astronauts though, more than 100,000 people have applyed for a one-way ticket to Mars in 2022. Since the journey isn’t a return trip, they shouldn’t have the same problem as the astro-jellies, although there are still other undesirable effects of long term space travel.
Microgravity (the term ‘micro’ means small) is a condition where the force of gravity is so weak that you feel weightless. This is seen in space where astronauts appear to float in the space shuttle, or on the moon.