The Giant Pacific Octopus (Enteroctopus dofleini) is regarded as the largest known species of Octopus. They have an average arm span of around 4m across and weigh in at roughly 50kg. They can grow even larger, with a deceased GPO being found in the wild weighing a whooping 272kg!
Giant Pacific Octopus habitats
Native throughout the Pacific, they inhabit the intertidal zone to depths of 2,000m. They live mostly in the benthic zone (at the bottom of a body of water). Preferring cold, oxygen-rich water. Areas such as California, Oregon, Washington, British Columbia, Alaska, Russia, Japan and Korea.
Cephalopods & Molluscs
Giant Pacific Octopuses are Cephalopods, which are active predatory molluscs, such as octopuses, Squid, Cuttlefish, and Nautilus. Molluscs are invertebrates with soft unsegmented bodies, many of which have an external shell. The likes of Snails, Slugs, and Limpets.
The word Cephalopod comes from the Greek language, it literally translates to “head foot” in reference to how its many arms connect directly to its “head” or mantle.
Curiously, Giant Pacific Octopuses actually have a shell, in the form of two small plates within their head.
Octopus Beaks
They also have a beak made of chitin, the same substance as insect exoskeletons and fungi cell walls. They use their beak to kill and eat their prey, as well as self-defence if required. Like all octopuses, the Giant Pacific is venomous, injecting venom into their prey through their beaks. However, it’s worth noting only the Blue-ringed Octopus venom is dangerous to humans.
Defence mechanisms
Giant Pacific Octopuses also have the ability to cloud any threats in ink. The ink is toxic and even deadly to the Octopus itself if it doesn’t have adequate water flow to clear it.
Masters of disguise
Giant Pacific Octopuses and other cephalopods are also fantastic at camouflage. Just below their skin, they have special cells called chromatophores. Chromatophores allow them to quickly change the colour of their skin. Which helps them to seamlessly blend into their environment, mimicking such things as algae-covered rocks and even seaweed!
Giant Pacific Octopuses are nocturnal, reducing the risk posed by predators. They need these varied defence mechanisms to help thwart the attempts of predators to eat them. Animals such as seals, sea otters, sharks, large fish and even human beings all consider the Giant Pacific Octopus food.
The “Hearts & minds” of Giant Pacific Octopus
Octopuses have 3 hearts, two that pump blood across the gills and one that circulates blood around the body. The blood they pump is blue, unlike our red blood. This is because it uses a copper-based protein called hemocyanin to transport oxygen around its body, unlike our iron-based haemoglobin. Octopuses breathe by drawing water in through the gills within their “Mantle” and out through holes behind their eyes.
If you thought 3 hearts was impressive, wait until you hear how many brains they have! Nine! That’s a main central brain within the mantle and a smaller “brain” at the base of each arm that can control each independently.
Life span and reproduction
Giant Pacific Octopus live an average of 4-5 years in the wild, despite this they are considered one of the longest living octopuses. Reproducing tends to be the last thing they do.
After mating, females lay an awful lot of eggs, around 100,000. Usually, this is in a cave or hidden deep at the bottom of the water. The females live there for 7 months watching over the eggs, without leaving them. Not even for food. They even gently move the eggs to ensure enough oxygen reaches them. When they hatch each of them is no bigger than a grain of rice. Growing nearly 1% a day.
Giant Pacific Octopus intelligence
Giant Pacific Octopuses are highly intelligent, being able to solve puzzles and mazes. They display a working memory of space over time, ranging in different directions to hunt for prey each night and remembering their way back home. Displaying emotions and personalities, even playing with toys.
Fortunately, Giant Pacific Octopuses are still rated as Least Concern on the IUCN Red List. The main threats they face tend to be over-fishing as bycatch. They’ll enter fishing pots to take advantage of trapped fish and tend to get stuck. Despite the fact, Giant Pacific Octopuses can squeeze their body down to sizes limited by how big their beak is.