Bdelloidea are microscopic aquatic animals that are related to roundworms, found in freshwater and moist soil. Interestingly, a male has never been observed within the species; females reproduce exclusively by parthenogenesis (without fertilization).
Anatomy of Tardigrada Demonstrating the appearance of gravid tardigrades, mouthparts, and different claw-forms and exterior textures. The Tardigrada of the Scottish Lochs: Transactions of the Royal Society of Edinburgh, Vol. XLI - Part III - No.
Award-winning images of some of the world's smallest life forms