Morphology and biochemical composition of eggs and paralarvae of the two-spotted octopus, Octopus bimaculatus

The study highlights the changes in the proximate composition and fatty acid (FA) profile of eggs and paralarvae and describes the chromatophore pattern and morphological changes in paralarvae. Ten gravid females of Octopus bimaculatus were collected in Kino Bay, Sonora, Mexico. Paralarvae were obtained from a single female laying event registered 90 days after capturing the organisms. Paralarvae were fed with rotifers and newly hatched enriched Artemia nauplii. Morphological description of paralarvae was performed based on Roper & Voss (1983) on 182 organisms collected over 10 days; mean values (mm) for total length, mantle width, head width, mantle length, arms length, funnel length, eye diameter and mouth diameter ranged from 3.66 to 4.86, 1.52 to 1.78, 1.48 to 1.84, 2.33 to 2.85, 1.02 to 1.58, 0.58 to 0.71, 0.44 to 0.63, and 0.10 to 0.14 mm, respectively. Organisms exhibited a characteristic chromatophore pattern of 4+2+2 (dorsal view), in addition to 24-30 and 39-51 chromatophores on the dorsal and ventral views, respectively. The proximate composition of eggs and paralarvae revealed two major components: moisture (78.99 and 82.26%, respectively) and crude protein (15.33 and 11.76%, respectively). The FA profile (mg FA g-1 wet tissue) of eggs revealed that 16:0 (3.39), 20:4n-6 (2.67) and DHA (1.67) were the most abundant, whereas in paralarvae 16:0 (2.21), 18:0 (2.37), 20:4n-6 (1.45), 20:5n-3 (1.98) and 22:6n-3 (2.18) were the predominant FA. This information contributes to the knowledge of the morphometric characterization and biochemical composition of O. bimaculatus eggs and paralarvae, providing a basis for further research.