Although the mechanism by which temperature modulates the use of reserves and its consequences for organogenesis in octopus species is not yet known, there is evidence that temperature modulates the embryonic growth rate in cephalopods with consequences for hatchling characteristics. The primary objective of this study was to investigate the effect of temperature (12, 15, 18 and 21 degrees C) on the duration of Octopus mimus embryo development and to generate a prediction model. The effects of temperature on size and physiological characteristics of embryos at stage XV were also studied. A third objective was to investigate whether temperature affects the time taken to reach stage XX using physiological time, i.e. degree-days (DD). The time taken to reach stage XV at 21 degrees C was 24,58 and 75% shorter than observed in eggs maintained at 18,15 and 12 degrees C, respectively. Logarithmic models were obtained for the relationship between embryo stage and age, demonstrating an inverse relationship between environmental temperature and the duration of embryonic development. Embryos maintained at 18 and 21 degrees C grew faster than those kept at 12 and 15 degrees C, although that growth rate was accomplished by an inverse relationship between yolk and temperature. The degree-day model suggests that between 128 and 133 DD should be accumulated when embryos are maintained at 15 to 21 degrees C. As in other invertebrate species the results on oxygen consumption indicate that embryos of O. mimus have a higher sensitivity to temperature than adults. The results suggest that the optimum range of temperatures for these embryos is around 15 to 18 degrees C. (C) 2012 Elsevier B.V. All rights reserved.