Life cycle of the marbled octopus, Amphioctopus aegina (Gray) (Cephalopoda: Octopodidae) reared in the laboratory

Reproducing small eggs and planktonic hatchlings is a reproductive strategy of many species of benthic octopods although it is considered a pleisiomorphic state. The young in the planktonic and settling phases have a high energy consumption and require live food of specific size range characteristics, causing difficulties in obtaining appropriate food organisms for rearing experiments through the entire life cycle. This study obtained information on details of life cycle characteristics of Amphioctopus aegina (Gray) by resolving these difficulties. The aspects of life cycle of A. aegina were similar to those of other benthic octopus with a similar reproductive strategy. Growth was allometric, consisting of 3 phases in terms of body weight, including a transitional phase for the early settling stage. Feeding and conversion efficiency peaked over a 2-month period prior to reproduction, representing the period of energy storage. Growth from hatching to spawning took approximately 74% of the entire life span and the reproductive phase itself took 34%. Such longevities are similar to those of other benthic cephalopods with planktonic hatchlings. Overall similarities in these cephalopod taxa attest to the fitness of a life-history strategy involving production of planktonic offspring from benthic adults. A. aegina is the second benthic octopus species with planktonic hatchlings for which the life cycle has been completed through rearing in the laboratory.