Maternal feeding history affects the trade‐off between offspring number and size for a holobenthic octopus

Female reproductive fitness has been clearly shown to be determined in part by a trade‐off between offspring size and number, and the corresponding performance of the offspring. The performance of offspring and corresponding reproductive fitness may vary in relation to changes in environmental conditions, such as food availability. In such a situation, maternal flexibility in allocating resources to offspring would help to maximize fitness. This study evaluated the effect of food availability on maternal mass, the number of eggs produced, maternal egg care behavior, and offspring size and growth for the webfoot octopus, Amphioctopus fangsiao . Females were fed either daily (HF) or on alternate days (LF) for up to 3 months before the onset of spawning, and after the onset of spawning, they were fed either continuously (CF) or not fed (NF), resulting in four different treatment combinations, that is, HFCF, HFNF, LFCF, and LFNF. The wet mass of female octopuses ranged from 54.3 to 155.6 g immediately before spawning but with no differences among treatments. Despite this, females in the HFCF laid twice as many eggs as females in the LFNF treatment, while females in the HFNF and LFCF treatment laid a similar number of eggs that were intermediate between the two other treatments. The larger clutches from the HFCF treatment resulted in 12%–20% smaller offspring at hatch compared to the other three treatments. In contrast to fecundity, egg care behavior was less affected by food availability with females caring for similar mean durations of care for their eggs in all four treatments. The results showed that egg care behavior appears to be largely independent of food availability, which most likely is a mechanism to guarantee adequate care and protection of offspring even under suboptimal conditions. It also appears that female A. fangsiao can adjust reproductive investment in response to their ambient feeding conditions, by reallocating energy into more or less offspring, that is, LFCF versus HFNF, respectively. Thus, the amount of food available to females prior to and post onset of spawning can have a profound effect on the trade‐off between offspring size and numbers for A. fangsiao .