Classification

Scientific Name — Octopus vulgaris

Common Name — Octopus or Devilfish

Domain — Eukarya

Kingdom — Animalia

Phylum — Mollusca

Class — Cephalopoda

Order — Octopoda

Suborder — Incirrina

Family — Octopodidae

Subfamily — Octopodinae

Genus — Octopus

Species — Octopus vulgaris

Domain - The Domain is quite straight forward.  An octopus is not a bacteria and therefore not in the Domain "Bacteria."  An octopus is also not an Archaea and therefore not in that Domain either.  An octopus is Eukaryotic and therefore it belongs to the Domain "Eukarya."

Kingdom - The Kingdom is also pretty obvious.  The octopus is an animal not a prokaryote or a protist.

Phylum - Molluska, this phylum contains snails, slugs, clams, oyster, nudibranchs, squid and of course octopuses.  All of these creatures have a head foot, a visceral mass, and a mantle.  Of the 75,000 species, 40,000 are aquatic or marine. 

Class - Octopuses are in the class Cephalopoda because they have a prominant head.  Cephalization is the term for having an anterior mouth and literally means "head foot".  The octopus has a completely merged head and foot with a ring of arms surrounding the head.  This group has the most complex brain of any invertebrate. 

Order - Octopoda; these guys usually have short compact bodies and have only eight arms.  All species are at least somewhat benthic and most live on the bottom their entire lives.

Suborder - There are two suborders; Incirrata and Cirrata.  The octopus is in the suborder Incirrata which contains 85% of the octopodan species.  The main distinction is that the Incirrata have no cirri which are large motor organelles of hypotrich cilliates form from fused cilia.  There are also no fins present and they have one or two rows of suckers on their arms.

Family - The Octopodidae are all benthic.  This Family unfortunatly is very diverse.  There are 24 generaly accepted genera.  Species in this family range from pygmy octopuses to the Giant Pacific Octopus.  A few main traits include: The internal shell is reduced or lost, the stomach is posterior to the digestive gland, and on of the third arm in males is modified to have an open sperm groove and a modified terminal tip.

Subfamily - This subfamily, Octopodinae, is characterized by the large "floppy" body/head region.

Genus - The genus Octopus is given to all species that fit the description of the above criterion.

Species - Octopus vulgaris or "The Common Octopus" is a smaller animal, 24-36 inches in length.  It has smooth skins and special pigment cells that allow it to change color to blend in with the environment.  This species lacks an internal shell.