I'm a little confused on something. If the O. Vulgaris lives around 12-18 Mo.s(If I read something that stated it wrong please correct me.) And the Bimacs live around 6-12 Mo.s, why do most people recommend the Bimac? Is it a question of availability? Also in the "Checklist: Things to Think About Before You Get An Octopus as a Pet" Nancy states that a Bimac should have at least a 50 gallon tank but only says that a Vulgaris would "require a much larger tank". What minimum size exactly is recommended for the Vulgaris? Thanks.