tardigrades are microscopic beings with a gift for survival. These aquatic invertebrates – also known as rasbora or moss piglets – can withstand high levels of radiation and crushing pressure deep seaand even the vacuum of space.
We also learned that water bears have some pretty wild sex, thanks to recent video footage from scientists Jacob Weissthe videographer for the YouTube channel Journey into the microcosm and author of “The hidden beauty of the microscopic world.”
Know who is one Expert in handling microscopes to study microbes in ponds, lakes, rivers and seas, created sealed environments on slides to observe the same tardigrades for weeks. So he took pictures of tardigrades that have mated up to two hours at a time.
He also picked up a 30 minute tardigrade threesome – one of the first known recordings of tardigrade group sex.
A water bear threesome
Researchers first published details on the mating behavior of tardigrades in a Paper 2016but other observations of water bear sex remain fairly limited.
“There weren’t many people studying tardigrades until recently, so all of these observations came from a few well-known tardigrade researchers,” Weiss said. (Yes, “tardigradologist” is a real word, he added.)
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“I don’t study tardigrades in a traditional, institutional way, but having been interested in them for a long time, I’ve collected a lot of data and observed unique behaviors,” Weiss said.
One of those unique behaviors? A water bear threesome.
In observing tardigrades on his slides, Weiss first noticed two smaller tardigrades that appeared to be attracted to the underside of a larger tardigrade. This was unusual, as tardigrades don’t usually show such focused interest in anything.
But even after 20 minutes, the two smaller tardigrades kept nudging the larger one with their mouths. Weiss, who is no expert on tardigrades but has seen enough of them in his studies of microscopic creatures, noted that the larger tardigrade looked like it was carrying unfertilized eggs.
He said the two smaller tardigrades were males who “fired their shot” to fertilize the females’ eggs.
As Weiss watched, he said the two males continued to sting the female while she pooped, which Weiss suggested might be a way to attract males.
However, Weiss added that due to experts’ limited understanding of tardigrade sex, it’s impossible to say exactly why she had a bowel movement.
“Water is all about chemical clues, so males have to gather some information to find females,” Weiss said.
To test this, Weiss separated some mating pairs by gently poking them through the slide and coverslip with some cat hair. In each case, the males returned to the females within minutes.
“So I think there are chemical signals, and well, when you poop, there’s a lot of signals that go out into the water,” Weiss said.
After a total of about 30 minutes, the threesome turned into a twosome when a man left the scene.
The remaining male stayed with the female for an additional hour, and Weiss observed similar mating behavior in other pairs of tardigrades on the slide.
Reproduction of water bears
Males are attracted to females with unfertilized eggs or ovules.
In his book, Weiss noted that men always seem to take the chase. “While the females quietly grazed seaweed, the males ran around like crazy chickens and hopped onto the females’ backs and stayed there for an hour and a half,” he wrote.
Once the males have found a female, they cling to her with their claws and the mates make a wild, rhythmic movement until the male finally finishes and releases thousands of sperm, which are likely to fertilize the eggs by entering an opening in the exoskeleton of the female penetrate.
However, scientists have yet to figure out exactly how fertilization occurs.
Not all tardigrades need to have sex to reproduce. said Weiss some species of tardigrades only include females, that reproduce asexually by parthenogenesis.
He also said it’s possible that tardigrades switch reproductive methods under environmental stress, although experts still have much more to learn about this theory.
But marine species of water bears, like the species recorded by Weiss, include both males and females, and they reproduce through mating.
birth of the water bear
A mother water bear might carry about 20 eggs before the eggs hatch one at a time — they pop like popcorn, Weiss said.
“Newborn tardigrades are easy to tell apart because they have empty tummies. They’re ready to breed in as little as a week, so it’s safe to say the babies will have babies two weeks after hatching,” Weiss said.
Tardigrades have relatively short lives, with 8 weeks being the longest lifespan Weiss observed in his research.
Check out the tardigrade threesome the following videostarting at timestamp 13:25.
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This article was originally published by Business Insider.
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