The bdelloid rotifers Philodina gregaria Murray and Adineta grandis Murray were both cultured through three generations. The results suggested the following models for calculation purposes: (1) that individual Adineta grandis live for 40 days and, at death, give rise to five offspring; (2) that individual Philodina gregaria live for 89 days, producing 18 young at three-day intervals, the first on day 36 and the last on day 87 (the animal dying two days later). Mathematical expressions for population growth were formulated, from these models, and used to interpret the field observations obtained from a shallow pool on Signy Island (60°43′ S, 45°38′ W) during the course of an Antarctic summer. Midway through the summer, two seals crawled through the pool and upset the continuity of the field study. This natural catastrophe not only provided an interesting insight into the recovery of such habitats but provided an opportunity to test further the hypotheses formulated in the culture experiments.