An octopus is an ocean dwelling mollusk in the cephalopod class. As the name suggests, the primary feature of an octopus is eight highly mobile arms, attached to a central bulbous body. Octopi can be found in all the oceans of the world, typically dwelling in shallow water, preferring the ocean floor as a habitat. In addition to serving as a food source, the octopus is also studied by many scientists, as it is believed to be the most intelligent of the invertebrates. The animals demonstrate an immense capacity for learning, logic, and reasoning, especially in controlled environments.
In addition to the arms and body, an octopus has a beak, a hard growth inside the body which is all that remains of the shell octopi may once have had. The lack of other hard structures makes octopi highly flexible, and allows them to fit in very small places. They also have complex eyes, which appear to be useful in low light environments, although octopi cannot see in color. The central nervous system of an octopus is highly developed, with several of the limbs operating almost autonomously from the brain. In addition, an octopus has three hearts, one to supply the body while two pump blood through the gills of the octopus, located under the protective mantle.
For a defense mechanism, an octopus has a sac of dark ink which it can eject at predators while it swims away, using propulsion. In addition, octopi can camouflage themselves by changing the color and patterning of their skin to blend in more thoroughly with their environment. Finally, an octopus can drop a limb if it is grasped by a predator, allowing the octopus to escape while the predator is distracted with the limb. The highly tactile arms of the octopus are equipped with sensitive sucker cups, which can transmit sensations to the octopus as well as assist it while it manipulates prey.
The life span of an octopus is relatively short; most of the animals live for five years or less. A male octopus will die shortly after it mates. A female will die after her eggs hatch because she does not eat while she looks after the eggs, which are fertilized under her mantle and then attached to the walls of her lair. When the eggs hatch, the young octopi drift in the open ocean before coming to rest on the ocean floor.
The arms, ink sac, and body of the octopus are all edible, although the meat of a larger octopus should be beaten to soften it. Many cultures integrate octopus into their cuisine, from small octopi used whole in sauces to much larger specimens which are cut up to be grilled, roasted, or fried. The meat is rich and flavorful, as well as chewy, but it can get rubbery if it is cooked too long.