Observations on the embryonic development of Octopus mimus (Mollusca: Cephalopoda) from northern Chile

The embryonic development of Octopus mimus Gould, 1852, was studied under normal upwelling temperature conditions (16 degrees C) and under conditions of medium and strong El Nino Southern Oscillation ((ENSO) events (20 degrees C and 24 degrees C, respectively). The embryonic development under high temperature conditions is faster than at lower temperature. Embryonic development of Octopus mimus under normal upwelling temperature conditions (represented by a constant temperature of 16 degrees C) takes about 35% more time than under conditions of medium ENSO events tar a constant temperature of 20 degrees C), and 62% more on average than under conditions of strong ENSO events (at a constant temperature of 24 degrees C). There were no abnormalities visible on the embryos developed at 24 degrees C. The hatching rate was high (estimated at about 95%). The higher temperature had no adverse effect on the viability of the hatchlings. This suggests genetic fixation of a wide temperature tolerance. The embryonic development of Octopus mimus is very similar to that of O. vulgaris Cuvier, 1797. However, egg and hatchling size, number of gill lamellae per demibranch, and heartbeat frequencies differ between the two species.