Morphological characteristics and length-weight relationship of common octopus Amphioctopus neglectus (Nateewathana & Norman, 1999) in the Halong bay, Quang Ninh province

Abstract

This study presents the analysis results of the morphological characteristics of the octopus species Amphioctopus neglectus based on 88 specimens (42 males and 46 females) collected from Halong bay, Quang Ninh province, in May 2022. The results show that the main taxonomic morphological features (body colour, funnel shape, arm length formula, web depth formula) of A. neglectus here are consistent with the reports of previous studies. For the first time, significant differences were recorded in 3 morphological indices between the two sexes of A. neglectus. The head width and sucker diameter indices in males were higher than in females, and the funnel length index of females was more extensive than that in males. The length-weight relationship of species A. neglectus had a close positive correlation according to the equation W=0.0006_*ML^2.7197. Since b<3, A. neglectus exhibits faster length growth than weight growth, and the growth coefficient of male octopuses (b=2.8114) is higher than that of female octopuses (b=2.6805). These findings have contributed to fulfilling knowledge of the morphological and taxonomic characteristics and growth of the octopus species A. neglectus.