The Giant Pacific Octopus

Displaying the “horns” that gave the species the nickname “Devil Fish”, a Giant Pacific Octopus nestles down atop a rocky reef in Barkley Sound on the West coast of Vancouver Island, British Columbia. Photo by John Rawlings

Tall Tales Are Told……..

“There I was. He was lookin’ at me…..I was lookin’ at him…..”and so, it began again. My long time friend and dive buddy, “Sparky”, began yet another tale of daring-do, regaling our captive fellow divers with a story of his underwater adventures stalking the enormous beasts of Puget Sound. As I continued to gear up I occasionally glanced in his direction, scanning the eyes of his audience as the story grew with the telling. Bemused, I noted that some were wide with awe, some held an obvious gleam of interest, while still others were clearly full of disbelief (having obviously labeled him as a BS artist). Inevitably, his stories always involve creatures of great size, designed to impress his audience. Having dived Puget Sound with Sparky for a number of years I know that, just as inevitably, his stories are true. On this particular day we were aboard a charter boat in search of one of the most famous of Puget Sound critters, the Giant Pacific Octopus. Our destination was “Sunrise Wall”, a beautiful site in the South Sound noted for Octopuses of great size. Throughout all my years of diving in our cold, emerald waters I have never failed to be thrilled at the thought of interacting with one of these marvelous giants. As we cruised along I could feel the boat’s diesels rumbling under the deck beneath me, and I could feel my excitement growing as well…..

You Saw One HOW Big…..?

The Giant Pacific Octopus is a cephalopod mollusc, a class that contains all other octopus, squid and cuttlefish. It is regarded as the largest species of octopus in the world. Until recently it was known as Octopus dofleini, but in 1998 was re-classified as Enteroctopus dofleini, part of a genus that includes all other giant octopus species. Rumors abound in the Pacific Northwest regarding the size to which E. dofleini is capable of growing, including one supposedly found dead years ago in the Ballard Locks in Seattle that is said to have exceeded 30 feet in local mythology. Tall tales aside, the most impressive “official” record that I have been able to locate is one from the Canadian Department of Fisheries and Oceans web site, indicating that the largest Giant Pacific Octopus on record weighed 272 kg (599.6 pounds!) with a total arm spread of 9.6 meters (31.5 feet!). Others have reportedly been found within the 300 to 400 pound range. These “records”, however, are disputed by many biologists, and in reality finding one that exceeds 100 pounds is extremely unusual. Generally, it is agreed that E. dofleini can reach a size of over 150 pounds, although a typical adult will be in the 60 to 80 pound range. Still, the size of the Giant Pacific Octopus is apparently limited only by the quality and quantity of its food……literally, if it eats well, it’ll GROW!

A Giant Pacific Octopus moves along a colorful wall at Sunrise Beach, a popular dive site in Puget Sound near Tacoma, Washington. It’s huge mantle and siphon are clearly visible in this photo. Photo by John Rawlings

Good Looking, Smart, and a Lot of Heart(s)!

Like all octopuses, E. dofleini has eight arms attached to the head/mantle area centered around a mouth. They have no bones – the only hard part of their body being a beak used to bite and kill prey. Each arm has rows of suckers along the full length to the tip. The arms are incredibly sensitive and have many nerves within them as well as in the suckers themselves. Octopuses can actually taste with their suckers and use them as one of their primary means of gathering information along with their excellent eyesight. E. dofleini has two rows of suckers per arm and can have as many as 1,600 of them. The mantle itself resembles a large bag that moves in and out as the octopus breathes. It contains the stomach and all of the other organs, including 3 hearts. Two of the hearts pump blood through the gills while the third pumps it through the body itself. When octopuses breathe in, water flows over the gills and fills the mantle, when they breathe out the water is forced from the mantle through a tube called a siphon. E. dofleini can force water through this siphon in such a manner that it can jet propel itself away from predators (or a too-curious diver) and have been known to travel large distances in this manner. Octopuses are known to be the most intelligent of the invertebrates and documentation exists that clearly shows evidence of curiosity, memory, planning, and even personality. Their skills include problem solving, stealth and mimicry and they have been known to open jars, make use of tools, and even to play. The Giants are also masters of camouflage, having specialized cells in their skin known as chromatophores that are under direct neural control. This allows them to change color in a matter of seconds based on their surroundings or situation, and also enables them to make patterns on their skin based on a series of rapid color changes. Further, they can raise or lower papillae on their skin, literally changing their texture in an instant. Combined, these abilities allow E. dofleini to rapidly change color, shape, position and texture from one moment to the next. When a diver witnesses such a spectacle it is one of the most beautiful sights in nature, but realistically speaking these capabilities are what make the Giant Pacific Octopus one of the most effective predators in the sea.

A Preference for “Fast” Food……

When it comes to food, E. dofleini and humans seem to share many of the same seafood preferences. In fact, when recently dining at a locally famous seafood restaurant near Seattle I was struck by how much the menu resembled a list of octopus favorites! In Puget Sound, the delectable Dungeness crab heads the list of preferred food items, but all types of shrimp, clams, crustaceans, fish and other molluscs are also on the menu. Octopuses are among the most mobile of the oceans’ predators and will travel extensively in search of their food. However, they will normally return to their den after their hunting expeditions, bringing their prey with them for “in-house dining”. One of the most certain signs of current or recent den occupancy is a large accumulation of crab shells and other shellfish debris near the mouth of the den. A den located in an area of particular food abundance can often have a midden of discarded and broken shells several feet high. Normally hunting at night, E. dofleini requires a heavy abundance of speed, stealth and skill to catch its favorite meal – Dungeness Crab are master sprinters and are capable of awe-inspiring bursts of speed when fleeing a hungry octopus (or diver!).

Although many different techniques are used by this highly intelligent hunter, typically the hunting tactics of E. dofleini involve a slow approach by stealth with each of the independent arms surrounding the unsuspecting victim, coupled with a sudden burst of speed in which the prey is enshrouded by the arm web and held in place with the suckers, encoloping  the crab in a “bag” formed by the arm webbing. Once the crab is grasped securely and unable to escape, the octopus secretes a substance called “cephalotoxin” into the bag that acts as a sedative – basically rendering the crab unconscious. The octopus will then either bite into the crab’s shell or simply pull off a leg or two. It will then inject an extremely powerful digestive enzyme into the crab. Since the crab itself is still alive at this point the crab’s own bloodstream pumps the enzyme throughout its body and it, in effect, literally digests itself on the octopus’s behalf. While this process is going on, the octopus simply waits. After approximately 15 to 20 minutes it will dismember the crab and “suck” out the “pre-digested” crabmeat. 

A Giant Pacific Octopus stares out at the author from within its den in Nootka Sound, British Columbia. The giants prefer habitat with plenty of rocky holes and clefts, but in a pinch will excavate dens in clay, sand or mud, or simply slither beneath any available underwater structure. Photo by John Rawlings

Prime Real Estate for Giants…..

Dwelling on the continental shelf of Western North America as well as Northern Japan and the Russian far-east, the range of E. dofleini extends in the United States from Southern California up the Pacific coast to the tip of the Aleutian Islands in Alaska. E. dofleini can literally be found everywhere within Puget Sound but have a decided preference for areas containing abundant food sources as well as the best denning opportunities. Dens are vital to these giants at virtually all stages of their development, so sites with abundant natural or artificial dens are extremely attractive to them. Most dens are found in naturally occurring holes, cracks or crevices within rocks or walls, although often E. dofleini will dig a suitable den in sand or under a log or rock if a ready-made den isn’t immediately available. Man-made objects are also popular as dens and octopuses can often be located within the nooks and crannies of wrecks, abandoned sewer pipes, and any other type of suitable debris. Small octopuses can also be found denning within bottles, jars or pipes on the bottom. Dens are usually only temporarily occupied, an octopus generally remaining in an area only so long as the food supply lasts. It will move on to greener pastures once hunting becomes difficult or foraging expeditions more far ranging. E. dofleini does not appear to be territorial, although smaller octopuses will generally retreat from a larger individual should one be encountered. The Giant Pacific Octopus is an asocial animal – they do not deliberately avoid each other, but they also do not seek each other’s company except when breeding is on the agenda. In areas where dens are scarce, competition for them may be intense and divers may find several octopuses near each other simply because of the close proximity of good den opportunities.

Using its arms to shield its delicate mantle, a Giant Pacific Octopus looks out at the underwater world from its den, in this case a cleft between two large rocks. Octopuses can literally fit into any opening larger than their “beak”, the only hard part of their bodies. Photo by John Rawlings

Sex and the Single Giant…..

Generally, males reach sexual maturity at approximately 26 pounds in weight and females at approximately 44 pounds. This will normally occur between 2 and 3 years of age. When a female is ready to mate it is believed she releases chemicals into the water column that in turn attract males to her. In the Pacific Northwest mating normally occurs in the Fall and pairs can often be sighted during that time. The third right arm of the male is modified with a sexual organ (ligula) that may develop to be fully 1/5 the length of the entire arm, (small wonder humans often find themselves envious of the Giant Octopus!). The ligula is used by the male to insert two large spermatophores (up to 1 meter in length) into the mantle of the female, who then stores the sperm in them for later use. Males may mate with multiple partners, but females appear to be selective – preferring larger males to smaller ones. Females will seek out a secure, rocky den and lay their eggs approximately 2 months after mating. Between 20,000 and 80,000 eggs are laid over a period of several days and are attached to the ceiling and walls of the den itself. The female will then remain in the den with her eggs, constantly cleaning, tending and aerating them with her siphon. She will not leave the den; even to seek out food for herself, despite the fact that incubation of the eggs can take as long as between 5 and 7 months. When the time arrives, she will induce the eggs to hatch by manipulating them with her arms and suckers. Her last act will be to blow the larvae out of the den with her siphon. E. dofleini females die immediately after the hatching of their eggs, having sacrificed all of their strength and energy in caring for their brood. Males are also not long-lived, and may survive only several months beyond mating. Generally, females live approximately 3.5 years with males around 4 years. After hatching, larval octopuses are approximately the size of a grain of rice and swim upward to become part of the heavy surface layer of plankton. There they will remain until they have reached a size at which they are capable of surviving on the bottom of the ocean – usually after about 6 weeks.

A female Giant Pacific Octpopus caring for her brood beneath the hull of a sunken boat in Washington's Puget Sound. The egg strands can clearly be seen hanging down like a curtain from the bottom of the boat to the left of her head. The female remains constantly with her eggs for months, refusing even food that is offered to her, protecting them and cleaning them tenderly until they hatch. As the thousands of tiny babies emerge, the mother's final act is to blow them out into the current with her syphon. Photo by John Rawlings

As was mentioned briefly above, male octopuses generally reach the end of their lives approximately a few months or so after the females, although in a far different manner. Males in the last period of their lives tend to head out and explore their surroundings, or as Dr. Roland Anderson of the Seattle Aquarium puts it, they “go on walk-about”! They often can be found during the Summer months out in the open during daylight hours, sometimes in small groups of similarly aged individuals, and will commonly approach divers as if satisfying their curiosity. The number of diver sightings of large octopuses markedly increases during this time period as both species (octopuses and humans) are increasingly “out and about” exploring and discovering their world.

A small Giant Pacific Octopus tries to make itself “invisible” by pressing itself into a depression on a rock wall in Puget Sound. Within seconds an octopus can assume the colors of its surroundings and only movement will betray its presence. Photo by John Rawlings

And Now, Back to Our Story……

In the distance the bright sunlight glistened off the snow covered slopes of Mount Rainier, virtually blinding us with its intensity as Sparky and I strode off the stern platform and dropped into the rich, green depths. By previous agreement we halted our descent at 90 feet of water and started a slow zigzag search pattern up the face of the wall looking for signs of octopus activity. As our lights scanned the rocks the beautiful colors stood out as if a mad artist had splashed his paints across them in a frenzy, the ambient sunlight filtering through the brown kelp adding to the overall effect. From the corner of my eye I saw my buddy snatch up a rock crab in anticipation of using it to tempt our prospective quarry out of its den. Midway through the dive I saw what we were hoping to find – a small opening in the rock face with a trail of crab and clam debris falling away from it like an expanding fan. Pausing by the opening of the den, my light briefly danced around the interior – someone was home! A large, rectangular eye surrounded by a dense tangle of suckers and arms peered back at me, the large mantle moving in and out with each breath. The size of the mantle and the largest suckers visible told us that it was a fairly large example of E. dofleini, probably between 60 and 80 pounds. Our host’s body colors and texture changed repeatedly as we attempted to get better views or to make physical contact.

Don’t Try This at Home, Folks……

As my buddy extended the crab toward the den entrance the Giant’s colors again immediately changed. Shortly, the tiny tip of a single arm began to snake out of the den, inching its way toward the tempting morsel. The color changed again as first contact with the crab was made and overall interest clearly increased. The tip of the arm began to wrap its way slowly around the crab, but Sparky slowly pulled the crab just out of reach. Within seconds additional arms began to creep out of the den as reinforcements. They, too, attempted to encircle the crab – only to have it again tantalizingly withdrawn. This impasse continued briefly for a while, each time a little bit more of the octopus coming into view. Suddenly, apparently deciding that enough was enough, the Giant literally poured out of the den like an expanding pool of oil, its arms wrapping around the crab and also extending up my buddy’s forearm. The game now took on an exciting new dimension! Being the kind of guy he is, Sparky pulled the crab back toward himself, the octopus immediately flowing toward him with its arms still attached, its mantle and leg webbing billowing out in an effort to expand its appearance and intimidate him. Literally face to face, the two rotated around as if in a dance, each of them embracing the other…..this Giant clearly didn’t have a problem playing with us, so long as a delicious crab was the ultimate prize! For longer than we would have ever dreamed possible the octopus remained with us, his arms crawling up and down my buddy’s torso and equipment as if gathering information for future reference, his colors seemingly changing with each new “discovery”. As the two of them shuffled about the bottom my camera shutter clicked happily away. The situation remained at this entertaining juncture until we began to approach our planned bottom time. Reluctantly, at that point Sparky released his hold on the crab and the Giant happily dragged it back into his parlor for a triumphant feast, (provided by an unpaid waiter!).

A diver offers a tasty morsel to a Giant Pacific Octopus in its den, and a single arm snakes outward to claim the prize. Interactions such as this can be extraordinarily wonderful – experiences that a diver will remember for a lifetime! Photo by John Rawlings

As we ascended toward the beckoning surface I occasionally glanced back down toward the den and its now satisfied occupant, wondering what the Giant inside was thinking about our just concluded encounter. Was it celebrating its triumph, pondering its place in the world, or just wondering “What the Hell was THAT all about?” E. dofleini had once again interacted with some more of those odd bubble-blowing creatures from the surface and seemed to have had a great time in doing so……what exactly do they think of us?

As I once again broke through the waves into the sunshine I saw that Sparky had made it to the surface a few moments prior to me. The grand story had already begun for those on the stern of the boat….. “Man, you should’ve seen that big guy come boilin’ out of that hole! He was lookin’ at me…..I was lookin’ at him…..”

The author would like to extend special thanks to Seattle Aquarium Marine Biologists Roland C. Anderson, PhD., (retired), and Jeff Christiansen for their assistance and input regarding the content of this article.

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