Morphological and Brooding Characteristics of Argonauta Argo Linnaeus, 1758 from Korean Water

One specimen of Argonauta argo belonging to the family Argonautidae, was collected Songjeong, southeastern coastal water of Korea on July 12, 2010. The specimen, a mature female of 76 mm mantle length and 97 mm shell length. The number of ribs are 56 in shell. The shell is distinct between the arm Ⅰ 's. The Ⅰ arm has expanded, hemi-discoidal web to which the distal part is fused together. The funnel is large and exceeds the base of arm Ⅳ . The arms formula is Ⅳ > Ⅱ ≒ Ⅲ > Ⅰ . The specimen was female. Fecundity was 155,203 eggs. This species is pelagic octopus and important prey item of dolphin.