Abstract:To explore the growth and development patterns during the early life period of Octopus vulgaris, the morphological characteristics of larva, juvenile, and young O. vulgaris under industrialized breeding conditions were observed and recorded. From hatching to 49 days of age, eight larvae were sampled randomly every two days, and total length, arm length, mantle length, mantle width, body weight, and sucker number in the longest arm were measured. In conditions of water salinity of 30~32 and 18.6℃~26.0℃, the average full length of the newly hatched larva was (3.05±0.11) mm; the yolk sac of newly hatched larvae was absorbed by the larvae themselves before hatching or within 9 hours after hatching; the 1-day-old larva just began to feed and the 17-day-old larva could feed on shrimp; at the age of 35 days, the larvae were ready for benthonic living; the body color of 60-day-old larva changed from transparent to milky white; at the age of 80 days, the body color of the larva is the same as that of the adult; the organs of 100-day-old larva were mature except for the gonads, and the morphological characteristics were consistent with those of the adult. The results showed that O. vulgaris larva (1~49 days of age) body weight exhibited a cubic function growth relationship with total length, represented by the equation: y=5×10–5x3–0.0009x2+0.0072x–0.0132; total length exhibited a linear growth relationship with arm length, represented by the equation: y=–0.0012x3+0.0492x2+0.0243x+0.2179; total length, body weight, arm length, mantle length, and mantle width exhibited a cubic function growth relationship with days respectively, with the regression equations: y=–0.0001x3+0.0105x2–0.0122x+3.0562, y=–2×10–7x3+4× 10–5x2–0.0004x+0.0034, y=–0.0004x3+0.0247x2–0.1037x+0.8214, y=–0.0004x3+0.0124x2+0.0749x+1.4757, and y=–3×10–5x3+0.0025x2+0.0354x+1.4026. We divided the early period of O. vulgaris into four developmental stages: Larvae octopus, juvenile paralarvae octopus, juvenile benthonic octopus, and young octopus. Each stage was determined by feeding style (endogenous or exogenous), morphological and biological characteristics, and ratio between arm lengths and mantle length.
