Octopi are highly intelligent invertebrates that belong to the cephalopod family. They are known for their complex problem-solving abilities and have been observed using tools, navigating mazes, and even playing games. Octopi have a unique anatomy, with eight arms and no internal skeleton, allowing them to squeeze through tight spaces and change color to blend in with their environment. They are found in oceans around the world and are popular in aquariums due to their intelligence and curious behavior.