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Much further information can be obtained by Googling on search strings like bdelloid rotifers dead-end (which is how I turned up the one quoted above). Copies of the above article can be downloaded as PDF from the PNAS web site at http://www.pnas.org/content/vol101/issue6/ .Sexual reproduction is nearly universal among multicellular organisms, and although asexual populations continually arise, they almost invariably suffer early extinction. The relatively brief evolutionary persistence of most asexual groups is seen in their failure to achieve high taxonomic rank and in the low degree of DNA sequence divergence between them and their nearest sexual relatives (1). Among higher-ranking animal taxa that have been considered candidates for ancient asexuality, many have proven on closer study to be sexual or of recent origin (1, 2). Thus, the abandonment of sexual reproduction is generally thought to be an evolutionary dead end. Against this generalization, however, rotifers of the class Bdelloidea stand out as an apparent exception. With some 370 described species (3, 4), they constitute the highest-ranking metazoan taxon in which males, hermaphrodites, and meiosis are unknown, eggs being formed from primary oocytes by mitosis (5, 6). The inference that bdelloids evolved asexually is further supported by the presence of chromosomes without morphological homologues and by the apparent lack of deleterious retrotransposons (5, 7, 8 ).
Apparently from the Greek βδελλα or bdella, meaning leech (also from Wikipedia).Bdelloids (pronounced with a mouthed and almost silent B rather like "deltoids" with a silent 't')
