Movement - Octopus vulgaris moves in two ways. The first is jet propulsion. Water is shot out of the mantle cavity very fast through the siphon. This allows the octopus to get quick bursts of speed to elude predators or catch prey. When not using this from of locomotion, the octopus can glide along the bottom using small undulating movements.
Senses - Octopus vulgaris has very good eyes. They have fully developed retinas and optic lobes. The eyes are the octopuses main sensory organ. Like most marine creatures the octopus can also feel vibrations in the water, but this sense is not as attuned as other animal's. The octopus also has a very complex brain which allows its to learn and problem solve. Depending on what the octopus senses it reacts accordingly. Most of the time the octopus reacts in fear, as do most animals. In which case the octopus can release a cloud of ink and use its siphon to jet away. The octopus can also used special skin cells to change colors to warn potential predators that it is angry and might attack or to camouflage itself. In some cases, octopuses react with curiosity to new stimuli and will carefully approach an object feeling it out with its arms. The octopus' arms are very sensitive and literally have minds of their own. Each sucker can move independently of the other and has a keen sense of touch.
Environment adaptations - The octopus' environment is hostile and difficult to live in. There are always predators about and to stay alive one must have a safe place to sleep and have defenses and adaptations so it can swim in the open to find food. Octopus vulgaris has no shell or skeleton to speak of. This being the case, it can fit into just about any size hole. The only thing is the hole has to be big enough to fit the octopus' hard beak through. Once the beak is through, the soft body can follow. This is very helpful when finding a place to live. It can get into small places and prefers very small cracks with a large interior space. once inside a small hideout, it is nearly impossible for predators to get them out. Another adaptation is defensive. The ink sac is only used if the octopus feels threatened. If scared the octopus will contract muscles around the ink sac expelling a murky black substance. This allows the octopus to use its jet propulsion to escape behind the inky curtain, leaving the possible predator with no idea where the octopus went.
Cool Colors - The octopus along with cuttlefish, and squid can change colors. They have special cells on the outside of their bodies that are kind of like an umbrella. When the umbrella is closed the animal appears a certain color, but when the cells open up like an umbrella, the different color shows and its looks as though the animal changed color. These cells can be opened and close up to five times a second on octopuses. This is known to be used as camouflage and as a mood indicator, but it is also thought to be used as a way of communication between buddies.