A globular head that can easily be distinguished from the rest of the body, which has 8 arms usually bearing suction cups. Octopuses have keen eyesight, their eyes are well developed and located on the sides of the head. There is a short protruding tube on one side of the head, under an eye, known as a siphon. The mouth is at the centre of the arms and has a beak, similar in shape to a parrot's beak, which is the only hard part of their body. The arms are initially united by a membrane. The common octopus can weigh up to 10 kg when fully grown.
At the end of the winter the sexually mature of the species move to shallower waters to reproduce. The female lays eggs (150.000-400.000) in long ribbons attached to the roof of her lair. She will stay there, taking care of the eggs for one to two months, not leaving for any reason, not even to feed. Soon after the eggs hatch, the mother octopus often dies of starvation. When in danger octopus squirt clouds of ink to confuse predators but more frequently rely their on exceptional ability to change colour.