First detailed observations on tardigrade mating behaviour and some aspects of the life history of Isohypsibius dastychi Pilato, Bertolani & Binda 1982 (Tardigrada, Isohypsibiidae)

In the present study we provide new insights into the mating behaviour of a bisexual tardigrade, Isohypsibius dastychi, revealing a process much more complex than expected. Mating included mutual stimulation that preceded semen ejaculation and egg deposition. If no mating occurred, egg absorption was observed. In addition, the life history and the influence of temperature on development were studied at two temperatures (12 and 20 degrees C). At both temperatures I.dastychi underwent three moults until adulthood with increasing inter-moult phases from the first to the third moult. As animals maintained at 12 degrees C became adults significantly later and also were significantly larger than animals at 20 degrees C, it is unlikely that either age or size determines the transition to adulthood. Generation time of females was significantly shorter than that of males, and both males and females were iteroparous. The consequences of our findings are discussed.