Limnodrilus hoffmeisteri Claparede, 1862 is a cosmopolitan Oligochaeta widely used as indicator of organic pollution in water bodies. Previous contributions have shown the effects of organic matter and temperature on the life history of the species, although very little is known about the factors that influence its reproduction. This study aimed 1) to test whether the larger weight of individuals results in an increase in the reproduction rate and 2) to test the influence of two granulometric fractions of sand on the reproduction and growth the species. In the first experiment, specimens of L. hoffmeisteri were separated in two groups with different average weights (small individuals = 6.63 ± 1.28 mg; large individuals = 12.44 ± 3.99 mg) and kept at 15 ± 1ºC for 21 days. The results of this experiment showed that the number of cocoons was statistically similar between the groups, but the mean number of eggs per cocoon produced by large individuals (2.78 ± 0.35) was greater than that produced by small individuals (7.45 ± 2.50). In the second experiment, weekly observations were conducted for 25 weeks in two groups of 30 specimens: one kept in fine sand and the other in medium sand, at 25 ± 1ºC. The single significant difference was in the number of cocoons per adult per day (0.37 ± 0.22 and 0.23 ± 0.24, for fine and medium sand, respectively). Individuals reared in fine sand produced a greater number of descendants compared to those reared in medium sand in the same period of time.

The biology of Branchiura sowerbyi Beddard, 1892 has been the focus of many studies in temperate regions, where the species is exotic, according to literature data. Due to its high productivity and easy cultivation, B. sowerbyi is of great interest as a food source for fish farming. The present study reports information on the reproductive biology and growth of B. sowerbyi under laboratory conditions at 25 ± 1ºC. Weekly observations during 52 weeks indicated that the time between cocoon laying and young hatching was 14 to 16 days, the specific daily growth rate was 0.91 ± 0.04% (mean ± SD) and the time to reach sexual maturity was 40.83 ± 6.88 days. As reported by other authors, the hatching rate observed was low (33.08%), but the survival rate of young was high, approximately 96%. Laboratory observations showed that B. sowerbyi has two annual reproductive cycles, the first (between the 5th and 24th week) being more pronounced than the second (between the 31st and 51st week) concerning the number of cocoons.