Bdelloid rotifers

Article By:

Gladyshev, Eugene A. Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts.

Arkhipova, Irina R. Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts.

Last reviewed:2010

DOI:https://doi.org/10.1036/1097-8542.YB100057

Bdelloid rotifers are microscopic freshwater invertebrate animals less than 1 mm in length. They are found in nearly every possible freshwater aquatic habitat, including those that remain wet for only a short period of time (Fig. 1). Originally discovered by Anton van Leeuwenhoek in the late 1600s, bdelloids were later noticed to possess no males. Four hundred described bdelloid species constitute the class Bdelloidea, which is a sister taxon to the facultatively asexual rotifers (that is, rotifers in which reproduction can occur asexually, but is not obligatory, being capable of adapting to different conditions to reproduce sexually) of the class Monogononta, in the phylum Rotifera. Bdelloids reproduce exclusively asexually, by parthenogenesis, whereby females lay eggs produced from resting oocyte nuclei after two mitotic divisions, not accompanied by chromosome pairing or reduction in chromosome number. Recently, new information on the molecular structure of bdelloid genomes has revealed their unique features, possibly conferred by their asexuality and unusual lifestyle involving repeated cycles of desiccation and rehydration.

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