Assessment of different anaesthesia techniques on Octopus americanus (Montfort, 1802) paralarvae

Guillaume Dupuy

Paralarva is a heavily studied life stage in some cephalopods in the hope of improving their wellbeing in rearing conditions. With the implementation of the European Directive 2010/63 and some ethical guidelines, cephalopods are to be protected under any circumstances from distress. Anaesthetics have been mostly used on cephalopods to avoid any negative reaction from tested individuals, but also in handling small-sized individuals such as paralarvae to be measured for their physiological and morphological characteristics. In this project, four different types of anaesthetic were tested on paralarvae of the redescribed species Octopus americanus: ethanol, magnesium chloride, mix of both chemicals, each at different concentrations and hypothermic solution at 10°C. Time was measured in order to define the efficiency of the anaesthetic by different attribute: induction, sedation, recovery and total recovery time. Significant differences were found in between anaesthetic in which fast induction and recovery where observed, however conditions were defined in order to choose the best product based on threshold time later discussed. In the end, ethanol at 10mL/L was found as the most efficient anaesthesia to be used on O. americanus paralarvae, a conclusion similarly drawn from previous findings on Octopus vulgaris, its morphologically similar species.