An octopus is a soft-bodied, eight-limbed mollusk of the order Octopoda, which consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Octopuses are sea animals famous for their rounded bodies, bulging eyes, and eight long arms. Here are some interesting facts about octopuses:

• Physical Characteristics: Octopuses are bilaterally symmetric with two eyes and a beaked mouth at the center point of the eight limbs. The soft body can radically alter its shape, enabling octopuses to squeeze through small gaps. Most octopus species have suction cups on the bottom of each arm, and the arms seem to have a mind of their own.

• Habitat and Behavior: Octopuses are found in every ocean of the world and along every coast of the United States. Most live on the seafloor, but some species are pelagic, which means they live near the water’s surface. Octopuses mostly feed on crabs, shrimp, and mollusks. They are solitary creatures that live alone in dens built from rocks, which the octopus moves into place using its powerful arms.

• Intelligence: Octopuses are highly intelligent animals, capable of learning, using tools, and remembering locations. They can match the colors and even textures of their surroundings, allowing them to hide in plain sight. Octopuses can also release a cloud of black ink, which obscures them and dulls an encroacher’s sense of smell. If all else fails, octopuses can lose an arm to an attacker and regrow one later.

• Etymology: The scientific Latin term octopus was derived from Ancient Greek ὀκτώπους (oktōpous), a compound form of ὀκτώ (oktō, "eight") and πούς (pous, "foot"), itself a variant form of ὀκτάπους, a word used for example by Alexander of Tralles (c. 525–c. 605) for the common octopus. The standard pluralised form of "octopus" in English is "octopuses"; the Ancient Greek plural ὀκτώποδες, "octopodes" (/ɒkˈtɒpədiːz/), has also been used historically.

In summary, an octopus is a fascinating sea creature with eight arms, a soft body, and a beaked mouth. They are highly intelligent and capable of learning, using tools, and remembering locations. Octopuses are solitary creatures that live alone in dens built from rocks, and they mostly feed on crabs, shrimp, and mollusks.