Ancient-asexual
Guides
Bdelloidea
Bdelloid rotifers, bdelloids
Bdelloidea is a class of microscopic rotifers found in freshwater habitats worldwide, comprising over 450 described species. These organisms are distinguished by obligate parthenogenetic reproduction—no males have ever been observed—and their remarkable ability to survive extreme desiccation through anhydrobiosis. They range from 150–700 μm in length and can remain dormant for years, with documented cases of revival after 24,000 years frozen in Siberian permafrost. Bdelloids have been called 'ancient asexuals' due to their estimated 25+ million year history of asexual reproduction supported by fossil evidence.