Why do octopuses change color?

Scientists have found that they change color when they want to attack. These creatures belong to the order of cephalopods. The body of these creatures is very soft. They have eight tentacles on their heads. Also, one cannot help saying that they have three whole hearts. But some species of these animals are simply poisonous. Some octopuses are thousands of meters long. The lifespan of these creatures rarely exceeds five years. These creatures prefer to live in rocky coastal areas.