Eight-armed cephalopods are a type of marine animal that includes octopi. Octopi are the most well-known of this group, and are characterized by their eight arms and two eyes. They are considered to be highly intelligent creatures, and have been known to use tools and solve puzzles. Octopi are found in many different habitats, from shallow coastal waters to the deep sea. They are also able to change color and texture to blend in with their surroundings.