The giant Pacific octopus (Enteroctopus dofleini) is one of the largest of the octopus species and resides in the northern part of the Pacific Ocean. It is mostly a solitary creature yet displays capacity for socializing.

Photography by Joel Sartore, National Geographic
  • The giant Pacific octopus, scientifically known as Enteroctopus dofleini, is one of the largest cephalopods in the ocean. On average, an adult is 4.5 meters (15 feet) from the tip of one arm to another. Each of its eight arms can be covered with up to 280 adhesive suckers, which are used to sense, to taste, and to detect their next meal.

    The octopus commonly preys on marine life such as clams, lobster, and fish. Its mouth, which is found at the apex of its arms, has a beak, used to take apart its prey. It also can release a toxin from its mouth to partially paralyze and digest prey, making it easier to pull apart.

    The predator becomes prey for a variety of marine animals, including sea otters, great white sharks, harbor seals, and humans. They are commercially fished in North America and parts of Asia, including Japan, both for food and as bait for fishermen (attracting species such as Pacific halibut). 

    The giant Pacific octopus inhabits colder Pacific ocean water near the coasts of Asia, in the area of Japan and the Korean Peninsula, north to Russia and east to Alaska, and south along the Canadian and U.S. coasts. They are benthic creatures, hunting along the seafloor, and can be found in a range of depths from shallow intertidal areas to more than 1,000 meters (3,280 feet).

    Although the population of giant Pacific octopus is not considered endangered, it is important to prioritize the health of intertidal ecosystems and minimize threats such as pollution, habitat degradation from human development, and overharvesting of marine species that the octopus needs to prey upon.

    1. How many eggs does a giant Pacific octopus typically lay at a time?

      Females usually only mate with one male in their lifetime. When ready, the female will find a male to mate within a den or cave where she will then lay tens of thousands of eggs at one time−sometimes up to 74,000 eggs or more−hanging in strands of a few hundred eggs each. The mother octopus will then live in this den for many months, sometimes close to a year, as the eggs develop while she protects and aerates them to provide nutrients. The mother does not eat during this time and usually dies shortly after the eggs hatch.

    2. How might ocean acidification affect the amount of available prey for the giant Pacific octopus?

      Ocean acidification is a process wherein the ocean is absorbing carbon dioxide (CO2) from the abundance of CO2 that humans have put into the atmosphere from the burning of fossil fuels. This absorption changes the ocean chemistry, and it becomes more acidic and lower in pH. This leaves fewer carbonate ions available for the giant Pacific octopus’ prey−such as crabs, clams, and other marine mollusks and crustaceans−that use carbonate to form shells and skeletons.

    3. Octopuses are known to be the grouping of invertebrates with the highest intelligence. What are some examples to show this?

      Some examples of octopuses displaying their intelligence are mimicking fellow octopus, recognizing humans they encounter repeatedly, opening jars, and solving simple puzzles.

  • Term Part of Speech Definition Encyclopedic Entry
    benthic Adjective

    having to do with the bottom of a deep body of water.

    endanger Verb

    to put at risk.

    prey Verb

    to target, victimize, or devour.

    suction Noun

    process of attracting a substance to a region of lower pressure.