Effect of hatching time and starvation on morphometrics and biochemical composition of Octopus tetricus paralarvae

Abstract

Rearing paralarvae of merobenthic octopus species from hatch to their benthic phase remains a difficult task, mainly due to unsuitable diets. Knowledge of their nutritional requirements is therefore crucial to providing appropriate diets. This study tracked changes in morphometrics and biochemical composition of Octopus tetricus paralarvae from the same brood that hatched at different times, and in starved paralarvae. Mean wet weight, dry weight, mantle length, arm length and protein content were highest in paralarvae that hatched at 0 days postfirst hatch, while the mean lipid content of paralarvae was not affected by hatching times. The mean wet weight of starving paralarvae continuously decreased, while the dry weight showed two distinctive declines between 0–1 dph and 3–5 dph. Both total length and mantle length were longest in paralarvae aged 0–1 dph compared to 4–5 dph under starving conditions. Paralarvae mean lipid content did not differ due to starving period but mean protein content decreased continuously. The most abundant fatty acids in paralarvae were DHA, EPA, palmitic acid and stearic acid across both experiments. The tendency of the protein content of developing and starved paralarvae to decline, while the overall lipid content remained largely unchanged, suggests that proteins were mainly catabolized, further indicating their importance for the formulation of artificial diets for octopus paralarvae.