On Nov. 25, 2015, scientists from the University of North Carolina at Chapel Hill announced they had sequenced the entire genome of the tardigrade (aka the water bear), for the first time. The research showed that approximately 6,000 of the tardigrade’s genes come from foreign species, which equates to around 17.5 percent.

The microscopic water creature grows to just over 1 mm on average, and is the only animal that can survive in the harsh environment of space. It can also withstand temperatures from just above absolute zero to well above the boiling point of water, can cope with ridiculous amounts of pressure and radiation, and can live for more than 10 years without food or water.

The foreign DNA comes primarily from bacteria, but also from plants, fungi, and Archaea. And it’s this incredible variety of genes that researchers suggest has allowed the water bear to survive in such extreme conditions. 

In December 2015, researchers in Scotland reported they had also sequenced the tardigrade genome, and found at most 500 genes from foreign species. They concluded that the original researchers might have inadvertently sequenced DNA from bacteria living alongside the tardigrades. Further research is needed to confirm just how foreign the water bear’s genome really is.