Classifying the Giant Pacific Octopus

Domain: EukaryaThis is a photo of eukaryotic fungus Boletus luridus. Owned by George Chernilevsky and can be found at
This domain is comprised of organisms that have a true nucleus. The nucleus contains the genetic material, which is made up of DNA. Each cell also contains membrane bound organelles, such as the mitochondria or chloroplast. This domain includes plants, animals, protists, and fungi.

This is a photo of kingdom animalia's panther. It is owned by Marcus Obal and can be found at
Kingdom: Animalia
Organisms in the kingdom Animalia are all heterotrophic. They are unable to produce their own food and must feed upon other organisms. Animalia are multicellular. They can produce sexually and are motile. This group contains animals all the way from sponges, to invertebrates, to humans. Other organism websites about animals include: the sea sponge, the panther, the polar bear, and the orangutan.

Phylum: Molluska    
Mollusks have bilateral symmetry and a soft body, which is frequently inside of a hard calcium carbonate shell. They have a nervous system, circulatory system, gills, and a pair of kidneys. This group includes: the amber glass snail, the magician's cone snail, the eightfold pinecone (a type of snail), zebra mussels, squid, and clams, to name only a few.

Class: Cephalopoda    
“Cephalopod” translates to “head foot.” These organisms have a closed circulatory system. They have flexible arms and a siphon. Cephalopods even have a large brain with ganglia located inside of a cranium. If there is a shell present, it is divided by septa. Other members of the Cephalopoda include: the squid, nautilus, and cuttlefish.  
Subclass: Coleoidea    
These cephalopods have an internal shell which is greatly reduced in size or is nonexistent. Squid and other octopuses are also included in this grouping.

Order: Octopoda    
 Octopodes have eight arms, hence the name “octo-poda,” which literally translates to “eight feet.” They also have a rounded body without a shell.  
Suborder: Incirrata   
This group of octopodes do not have fins, unlike the members of the alternative suborder, Cirrata.

Family: Octopodidae    
Organisms in this family have suckers which are in groupings of one or two. They have a stomach and caecum that follow a digestive gland. If they have lateral teeth on their radulas, the teeth have only one cusp. The males of this group have a modified third arm into a hectocotylus. Their hectocotylus is not detachable. This group includes all of the classic octopuses that even children can imagine, including the common octopus: Octopus vulgaris.

Genus: Enteroctopus    
The members of this genus are known as “giant octopuses.” They have large bodies with longitudinal wrinkles or folds. Giant octopuses’ heads are narrower than the width of their bodies. They also have paddle-like shaped papillae instead of the rounder version found in other genera. Enteroctopus megalocyathus and Enteroctopus magnificus are a couple of the giant octopuses closely related to E. dofleini.

Species: Enteroctopus dofleini    
Enteroctopus dofleini is the specific scientific name of the organism this entire website is devoted to. There are many characteristics that make it unique. Keep reading to learn more.

 Enteroctopus dofleini Phylogenetic Trees  


The Pacific octopus was recently re-classified. Previously, it was named Octopus dofleini. But, it has been moved into the new genus, Enteroctopus, along with all of the other giant octopuses of the world. 

         This is a photo of the Pacific Octopus’s phylogenetic tree from Eukarya to Molluska. Created on 3/25/12 by Julie Kalupa.

    This image depicts the relationship between all of kingdom Animalia's phyla. It shows how E. dofleini travels from kingdom Animalia to phylum Molluska via the purple line. This tree uses cladistic method of classification to arrange the branching of the phyla depicted above. The cladistic method means that they are arranged based on their molecular data, or DNA genotype. This phylogenetic tree shows this organism evolves farther away from the Porifera, or sponges, and toward the Chordata, or humans.
    The octopus has evolved away from the tissue-less asymmetrical body style, and toward the endoskeleton with bilateral symmetry style. However, the octopus is still an invertebrate. This characteristic becomes clear when one realizes that this organism is still quite far away from the phylum Chordata, and that all phyla to the left of phylum Echinodermata are invertebrates. E. dofleini does, though, display the evolutionarily-advanced characteristic of bilateral symmetry.
      Phylum Molluska's closest relative phylum is Annelida. Phylum Platyhelmintha are also close relatives of the mollusks. These three phyla are said to be closest related since they all branch off of the same line. In conjunction, Arthropoda and Nematoda are quite close relatives of these three phyla, too.
     Alternatively, a great example of convergent evolution compares the Pacific octopuses’ eyes with humans’. It is a great depiction of convergent evolution because both species' eyes turned out very similar, yet neither of them were passed down from a common ancestor. This means that each species evolved their own style of eye, while both species were existing at the same time. Yet, the eyes miraculously ended up being extremely similar in both anatomy and physiology. Since no other phyla between Chordata and Molluska have creatures with camera eyes, this characteristic can be labeled as a polyphyletic characteristic that connects the two, very different, species.


     In this tree, E. dofleini is followed from phylum Molluska all the way to the the genus Enteroctopus. This tree also uses a cladistic approach. It can be easily viewed in the way that the subclass Coleoidea are very separated from the close-relating subclasses of Nautiloidea and Ammonoidea. At this particular part of the tree, the Pacific octopus is separated from the shelled cephalopods.
    Order Octopoda is closest related to the Vampyromorpha. This order contains a single species of squid that are not grouped with the other squid, which are in Decapoda. Decapoda separates the organisms with ten extremities from the ones with eight, the Octopoda. The family and genus rows of this tree are not complete. There are many more families and genera than were able to be viewable in the above image.
   Through evolution, the mollusk E. dofleini has lost its calcium carbonate exoskeleton. It has also developed eight muscular arms. The circulatory system has converted from open to closed. Also, the nervous system has greatly advanced to include a functioning brain with nerve cords. E. dofleini has, through evolution, distanced itself greatly from its close relatives, especially the snails and clams.

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 Julie Kalupa of University of Wisconsin - La Crosse.  BIO 203 - Spring 2012