Tardigrades are a nature’s wonder, capable of withstanding extreme temperatures, pressure, radiation as well as acute desiccation. Measuring somewhere between 0.3 and 0.5 mm in length, these tiny organisms, also known as water bears, are famous as the first known animals to actually survive in space. Thanks to a new study, we now have a fascinating footage of these creatures mating, which the scientists believe is even more bizarre than it appears.
Existing research shows that many tardigrade species are in fact bisexual, with fertilization actually occurring outside the organism’s body. To unravel some of the mysteries surrounding this microscopic animal, a team of scientists from Germany’s Senckenberg Museum of Natural History has recorded its mating process for the very first time. In the video, one can see the male water bear ejaculating into a spot underneath the female’s skin. Speaking about the discovery, the researchers explained:
In the present study we provide new insights into the mating behavior of a bisexual tardigrade, Isohypsibius dastychi, revealing a process much more complex than expected. Mating included mutual stimulation that preceded semen ejaculation and egg deposition.
The findings, which were recently published in the Zoological Journal, reveal that the mating process commences with the female tardigrade laying eggs during its moulting period, which is the time when the animal sheds its outer dead skin. According to the scientists, the discarded cuticle actually holds the eggs. Following this, the male takes his position around the female, a process that culminates in the former ejecting his semen through what appears to be a slit right above his anus, and into the female’s dead skin layer.
This in turn points to the fact that fertilization in water bears takes place outside the mother’s body. In the absence of mating, the eggs are sucked back into the female body. As explained by the researchers, the rate at which the offspring grow depends on the temperature at which the adults mate. Despite this amazing discovery, there’s still quite a bit that remains unknown. For instance, how does the male aim his semen directly into the pouch containing the eggs?
Watch the following video to see these tiny super animals going at it: