 The mantles of bigfin reef squids are cylindrical , tapering to a blunt cone at the posterior . The mantle is usually 4 to 33 cm ( 1 @.@ 6 to 13 @.@ 0 in ) long in males and 3 @.@ 8 to 25 @.@ 6 cm ( 1 @.@ 5 to 10 @.@ 1 in ) long in females . Both sexes can reach a maximum mantle length of 38 cm ( 15 in ) . Adult males weigh 403 @.@ 5 to 1 @,@ 415 g ( 0 @.@ 890 to 3 @.@ 120 lb ) , while adult females are 165 to 1 @,@ 046 g ( 0 @.@ 364 to 2 @.@ 306 lb ) . Both sexes can attain a maximum documented weight of 1 @.@ 8 kg ( 4 @.@ 0 lb ) . The forward margin of the mantle on the ventral side is concave . 
