Non-marine ostracods are small, bivalved crustaceans with a wide range of reproductive modes and an excellent fossil record because of their calcified valves. Fossil data indicate that the family Darwinulidae might have been asexual for 200 million years (Martens et al., 2003), whereas it type species, Darwinula stevensoni, has survived without sex for at least 25 million years (Straub, 1952), making it the oldest known asexual animal species. Here, we will present an overview on our genetic and ecological research. This will illustrate that D. stevensoni and other darwinulids have been able to counteract the expected accumulation of mutations because of homogenising mechanisms such as gene conversion (Schön & Martens, 2003; Pinto et al., in press) and possible highly efficient DNA repair systems (Schön & Martens, 1998). The presence of a general purpose genotype in several darwinulid species (Van Doninck et al. 2000, 2003) demonstrates how ancient asexuals can persist over long evolutionary time frames even if they cannot react as quickly to environmental changes as sexuals. In addition, we will present novel data (phylogenetic and other) to show that the three recently discovered males of the species Vestalenula cornelia are no counterevidence against ancient asexual status of the Darwinulidae as a whole.