Returning from space isn't confusing only for humans. Non-terrestrial animals like jellyfish even have a hard time with the return to gravity.
An article by RR Helm in Deep Sea News pointed our way to some interesting research from the 90s on what happened to jellyfish that were born in space. Sending jellyfish to space might seem silly, but these simple animals have given scientists plenty of insight into the effects long-term zero gravity exposure.
If humans colonize space, it is possible that children could eventually be born and raised in zero gravity. This could mean that humans born in space never develop a normal sense of balance or normal muscle response to gravity.
Even though they don't have legs and live in the ocean, jellyfish are sensitive to gravity just like humans. So scientists bred jellyfish — a species appropriately named moon jellyfish — in space and brought their babies back to Earth to see how they fared. The 1994 experiment was detailed in a study published in Advances in Space Research.
Jellyfish are full of graviceptors — small crystals of calcium sulfate stored in pockets surrounded by sensitive hair cells. When a jellyfish changes direction, the crystals respond to gravity and roll around to the bottom of these pockets and signal the hair cells which way is up.
Of course gravity has to be present for these crystals to work.
When they baby jellies returned to Earth, they had a hard time getting around. The space jellyfish had more trouble orienting themselves and moving around than their Earth-born relatives.
Their gaviceptors seemed to look normal, so the researchers think there must be some way in which they were calibrated wrong, or were connected to the jellie's nervous system incorrectly.
The human inner ear contains fluids and cyrstals that function in a similar way to jellyfish graviceptors. The inner ear crystals signal what angle our head is at and give us a sense of our forward momentum. Like the space born jellyfish, humans raised in zero gravity may have trouble moving around normally if they returned to Earth.
A surprising number of animals have been bred in space, including frogs, salamanders, and sea urchins. Fish and tadpoles swam in loops instead of straight lines when they were taken to space, according to NASA.
More recently animal space research focused on rats. In 2007 Jeffrey Alberts worked with NASA to study how spending the last week of gestation in space would affect newborn rats. Alberts found that rats who spent a week in the womb with zero gravity couldn't tell up from down when they were first born.
The baby rats were unable to flip themselves right side up when they were dropped in water, but eventually recovered a normal sense of gravity.
A study published in PLoS ONE in 2011 described how snails fared when they returned to Earth. Snails also have gravitoceptors like humans, but snails born in space ended up growing really large gravitceptors — probably to compensate for the lack of gravity.
When the space snails were tilted or turned upside down, they actually started trying to turn themselves right side up faster than their Earth-born relatives, but not always in the right direction. The scientists concluded that being born in space made the snails more sensitive to gravity changes, but they could not tell which way was up.
More research is needed before we can fully understand how growing up in space could impact a human. But you can figure it's going to be weird.
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