Scientific Name: Order Octopoda
Description: The octopus is a mollusk in the class Cephalopoda. Cephalopoda means “head foot” in Greek, and in this class of organisms the head and foot are merged. A ring of eight equally-long arms surround the head. The arms are covered on the underside with suction cups that are very sensitive to touch and taste. The sack-like body is perched atop the head, which has two complex and sensitive eyes, while the mouth is on the underside. Octopuses have a hard beak which these use to pierce the shells of crustacean prey.
Octopuses have three functioning hearts. Two of the hearts work exclusively to move blood to the gills, while the third pumps blood through the rest of the body. They have copper-based rather than iron-based blood, which is more efficient at transporting oxygen at low temperatures and makes their blood blue in color.
Octopuses are solitary creatures excellent at camouflaging and concealing themselves. They are about 90% muscle, and because they lack bones they can fit through very small spaces. Their skin contains cells called chromatophores that allow the octopus’s skin to change color and pattern. They are believed to be quite intelligent—capable of learning, using tools, and remembering locations.
Octopuses move through jet propulsion—they suck water into their mantle cavity then quickly contract muscles to force the water out through a narrow siphon, aiming the water to steer in a particular direction. They also ‘walk’ on their many arms.
Size: There is tremendous range in the size of octopus species found in U.S. waters. The giant Pacific octopus (Enteroctopus dofleini), found off the Pacific coast of the U.S. from California to Alaska, is the largest octopus species in the world. It has an arm span that can reach 14 feet. The common octopus (Octopus vulgaris), found along the east coast of the U.S., is much smaller, growing up to about 3 feet. The red octopus (Octopus rubescens), found along the Pacific coast, grows to about 20 inches.
Diet: Newly hatched octopuses will eat small foods such as copepods, larval crabs and seastars. Adult octopuses are feed on crabs, clams, snails, small fishes and even other octopuses. All species of octopus have venom of varying levels of toxicity which they inject using a beak that is similar to a bird’s. They typically hunt at night. They pounce on their prey, wrapping it in the webbing between their arms. They penetrate hard-shelled prey with their beaks.
Predation: Moray eel, fish, seals, sperm whales, sea otters and many birds prey on octopuses. Octopuses use many strategies to evade predators—they camouflage themselves by quickly changing their skin color, they make colorful displays or eject ink to startle or confuse potential predators, they can squeeze into small crevices to escape and they propel themselves through the water very quickly.
Typical Lifespan: An octopus will generally live for about 1-3 years, depending on the species.
Habitat: Octopuses live in coastal marine waters and spend much of their time in dens--small holes and crevices in rocks and coral. They are generally solitary and territorial.
Range: Octopuses are found in every ocean of the world and along every coast of the United States.
Life History and Reproduction: The male initiates mating by approaching the female. He has a specialized tip at the end of one arm that transfers sperm to the female’s oviduct. The female looks for a suitable den site and lays the eggs attached in chains to the rock or coral or the den. The eggs can number in the hundreds of thousands for some species. The female guards and cares for the eggs, aerating and cleaning them, until they hatch. As soon as they hatch the young are able to swim, eat, produce ink and other things adults can do. The male parent dies soon after mating and the female survives only until her brood has hatched.
Fun Fact: ‘Octopus’ means ‘eight-footed’ in Greek. Contrary to popular opinion, the plural of ‘octopus’ is not ‘octopi’ but ‘octopuses’, as the word ‘octopus’ comes not from Latin, but from Greek.
Conservation Status: Octopuses are spread throughout a large ocean area and are solitary, which makes it difficult to determine the status of their populations. They are not believed to be under threat, but they are sensitive to pollutants. Scientists are still discovering new species of octopuses.
The Amazing Octopus infographic, National Aquarium
Cephalopod Lesson Plans
Common Octopus Changing Color, ARKive
The Science Behind Understanding the Giant Pacific Octopus, NOAA Fisheries Alaska Fisheries Science Center
Cephalopods, Animal Diversity Web, University of Michigan Museum of Zoology
Common octopus, Octopus vulgaris, Animal Diversity Web, University of Michigan Museum of Zoology
Giant Pacific octopus, Enteroctopus dofleini, Animal Diversity Web, University of Michigan Museum of Zoology
Giant Pacific Octopus, National Aquarium
Giant Pacific Octopus, Smithsonian National Zoological Park
Octopus, Hawaiian Marine Life, Maui Ocean Center
Octopus briareus, Animal Diversity Web, University of Michigan Museum of Zoology
Octopus joubini, Animal Diversity Web, University of Michigan Museum of Zoology
Red Octopus, Monterey Bay Aquarium
Ten Curious Facts About Octopuses, Smithsonian Magazine
The Elusive Giant Pacific Octopus, NOAA Fisheries Alaska Fisheries Science Center
What Behavior Can We Expect of Octopuses?, by J.A. Mather and R.C. Anderson, The Cephalopod Page