Principal Component Analysis of the Morphometric Traits of the Cuttlebone of Sepia esculenta at Early Developmental Stages

Abstract:

To characterize the traits of the cuttlebone of Sepia esculenta at the early developmental stages, we collected data at different stages including the red-bead and black-bead stage, the heart-beating stage, the hatching stage, the newly-hatched larvae stage, the 5-day-old stage and the 10-day-old stage. The principal component analysis was performed to evaluate seven growth traits including the dorsal mantle length, the mantle breadth, the body weight, the cuttlebone length, the cuttlebone breadth, the cuttlebone weight and the lamella number. The results showed that there were significant correlations between any two traits at the red-bead and black-bead stage, the hatching stage and the 10-day-old stage. However, some traits showed no correlation at the heart-beating stage, the newly-hatched larvae stage and the 5-day-old stage. The first principal component was the weight factor at the first two stages, and it became the length factor at other four stages. The second principal component was the length factor and width factor. The third principal component was mostly the width factor. At only two stages there was the fourth principal component that was the lamella factor and the width factor. The growth rate of these traits varied at different stages. From the red-bead and black-bead stage to the heart-beating stage, the morphometric traits outgrew the body weight, and this pattern was reversed from the hatching stage to the 10-day-old stage.