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Regions > Americas > Giant Pacific octopus
Giant Pacific octopus
Location at the Zoo: Americas
Region: Northern Pacific
Scientific Name: Enteroctopus dofleini
The Giant Pacific octopus has a huge, bulbous head and is generally reddish-brown in colour. The size record for this species is held by a specimen that was 9.1 m across and weighed more than 272 kg. However, its size usually averages about five metres and weighs approximately 50 kg.
Both sexes are similar in appearance; except that the male has a groove on one tentacle (the hectocotylus) which carries spermatophores (packets of sperm). Octopuses are invertebrates with soft bodies. The mantle covering the body cavity (which encloses the gills, heart, etc.) is a complex membrane surrounded by eight tentacles (arms), each covered on the under surface with two rows of suckers.
Enteroctopus dofleini inhabit the continental shelves of the North Pacific Ocean, from California to British Columbia, Alaska, the Kodiak Islands and Japan. They live in water from 8 to 13 ˚C. The species occurs at depths from the inter-tidal to 750 m.
They will inhabit any den-like space on the ocean floor, such as natural caves with narrow openings. They are also found in discarded barrels, tires, sunken ships and when young, in cans and bottles. Dens are required for both protection and brooding chambers, so the availability of suitable den sites is a major factor in determining the population in any given area.
They consume mostly crustaceans and molluscs, and apparently favour crab and shrimp. Bivalves, snails, fish, and other octopus are also eaten.
Reproduction and Development :
When the male places his spermatophore in the female's body cavity, her eggs are fertilized and expelled in clusters which she attaches to the top of her cave by fine strands. She deposits thousands of eggs over a period of time, during which she does not leave her den even to eat. The female cares for the clusters of eggs by providing oxygen to them with water from her funnel. In four to six months, the young hatch and are fully developed and independent. Many are eaten by other inhabitants of the ocean floor, leaving few survivors. Females are fertile only once - they die soon after the eggs have hatched. The male also dies two to three months after mating. Although the Giant Pacific octopus lives longer than most other octopus species, its maximum lifespan in the wild is still only three to five years long.
The Giant Pacific octopus can use special pigment cells in its skin to rapidly change colours and textures, and can blend in with even the most intricately patterned corals, plants and rocks. Because they are invertebrates, even the largest octopus can squeeze through very small openings. This ability is especially useful when fleeing from predators, or trying to escape captivity. An octopus can squeeze into a variety of protective homes.
The octopus can use its tentacles to pull apart shells. If this proves to be too difficult, they can use their hard beaks to either crack or drill into the shells. They also have specialized salivary glands that produce venom used to immobilize their prey. Their digestive system contains both a crop and a caecum, both of which aid in digestion.
By day, it spends time sleeping and can slow its heart rate from 32 to 13 beats per minute. At dark, it emerges to hunt. Octopus stalk their prey with their prehensile arms spread like an umbrella and tips curled. In open water the octopus is vulnerable and uses jet propulsion in order to escape danger.
When frightened, the octopus contracts the mantle muscles, and water in the body is expelled through the funnel tube and jetting occurs. The octopus can also eject a slimy, black ink through the siphon which acts as a smoke screen, enabling it to evade enemies. In addition, this octopus is quite intelligent and can often outwit its enemies. In addition, they have excellent sight, smell and taste, but they cannot detect sounds.
Threats to Survival :
Depending upon their size and age, predators include other octopuses, various fishes, sea otters, seals, and sea lions. Few of the young survive, but once an octopus is fully grown, it has few predators. However, sperm whales and humans will hunt them at any stage of their lives. Pollution may pose problems to localized populations, but the species as a whole is not endangered.
IUCN: Not Listed ; CITES: Not Listed
Zoo Diet :
Scallops, jumbo shrimp, filet of sole, and blue crab.