An octopus is classified as follows:

• Domain: Eukaryota
• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Octopoda
• Family: Octopodidae
• Genus: Octopus
• Species: There are over 300 species of octopuses, with the most common being Octopus vulgaris).

Octopuses belong to the class Cephalopoda, which also includes other molluscs like squids and cuttlefish. They are characterized by their eight arms and soft, bilaterally symmetrical body with two eyes and a two-part beaked mouth.