Creature Feature: Giant Pacific Octopus

How Do They Grow and Reproduce?

These introverted invertebrates wrote the book on social distancing. While they will occasionally make an exception, and cling to one another during mating, they don’t have to. They often prefer to get on with the process through a simple handshake. Well, maybe it’s not exactly a simple handshake, but the male reproductive organ, containing his gelatinous pencil- shaped spermatophore packets, does reside in one of his arms—the third right one—called the hectocotylus. So if his den is close enough to that of a willing female, he doesn’t even have to leave the comfort and safety of his living room. This scenario also renders him a lot less likely to get eaten alive by his partner. Nevertheless, octopus courtship is usually more similar to the human style, in that it is accompanied by special displays to attract the attention of potential partner, including change in skin texture and color, and demonstration of skill. Once granted access by a female, a male may use his special arm to remove anybody else’s spermatophore, and deposit his own, into her mantle cavity. All this amorous effort exhausts him, and he dies within a few weeks or months of breeding, whether or not his mate is particularly ravenous or irritable.

About 40 days after being impregnated, the female hangs her two litres of delicate, rice-sized eggs (between 10- and 70,000 of them) from the ceiling of her den, like lacy white curtains or strings of party lights. Then she cares for them, cleaning, aerating, and literally guarding them with her life, for about the next five months. In colder subarctic waters, eggs may take up to 10 months to develop. If left unattended, a majority of her eggs will not hatch. So during this brooding period, she subsists solely on the fats and proteins of her own body, fully consuming herself over the course of gestation. Shortly after her eggs hatch, she dies.

Baby Giant Pacific Octopuses are planktonic and drift around in the water until they are about 50 mm/2 in long. Then they descend to the bottom, and continue to mature for two to three years, living up to about five years.

Everything comes back to complex optics with octopuses, and the optic gland is thought to also secrete hormones that cause them to mature, age, and stimulate procreative capacity. Thus environmental factors such as temperature, light, and available nutrition can greatly affect octopus reproduction and lifespan.

Trivia: What Makes Them Special?

Octopus in Barkley Sound recovered from a prawns trap
Photo from Blair Mitchell, April 2020

Octopuses have three hearts: a systemic heart for pumping blood throughout most of its body, and two branchial hearts for circulating it through the gills. The systemic heart is inactive while the octopus swims, which causes it to tire quickly. In addition, octopus blood contains a copper-rich protein called haemocyanin, which carries oxygen more efficiently than haemoglobin in cold environments, and gives it a bluish colour. It also makes it viscous, requiring considerable pressure to pump. This may be the reason it is such a lackadaisical homebody.

Octopus’s Garden

Octopuses are drawn to shiny objects, and have often been observed collecting and arranging these and other curiosities in and around their dens. There’s no known reason for these little “octopus gardens” other than a possible penchant for home decorating. But they can alert a keen observer to the presence of an octopus lair, and they inspired the Beatles’ Ringo Starr to write a catchy tune.

Octopus Intelligence

Octopuses can make strategic decisions, recognize individual humans, navigate mazes, and solve certain types of puzzles. They have been known to board fishing boats and open holds to munch on crabs. In aquariums, they have even been observed playing with LEGOs, and releasing objects—such as rubber duckies—into a circulating current, and later catching them. Not surprisingly, they also have had success in breaking out of aquariums, and in exploring other tanks and nearby labs, where they have opened doors and lids, and disassembled equipment. Jaques Cousteau wrote of an octopus who escaped into a friend’s library, where it removed books from the shelves and turned the pages.

Octopus Brain

Widely considered the most intelligent of all the invertebrates—and smarter than most vertebrates, as well, octopuses have nine brains… sort of. Protected within a donut-shaped cartilaginous capsule, the central brain of an octopus—which some contend is its only “true” brain—controls and coordinates the nervous systems, while a smaller, auxiliary “brain” in each limb controls the movement and sensory perception of that limb. But as we discussed earlier, each of these limbs can operate independent of the octopus’s head and mantle, even after being disconnected. In reality, the arm-brains are more analogous to the brain stems of humans and other vertebrates, being responsible mostly for reflexive action as opposed to conscious decision. In similar fashion to how we can walk, digest food, and feel a breeze without really thinking, any of an octopus’s limbs can sense prey and try to capture and taste it without input from the command center. Of course, they can also function in a coordinated manner, when required. In any case, the arms contain two-thirds of octopuses’ neurons.

The brain capsule encircles the animal’s esophagus, so when octopuses bite off more than they can chew—or more accurately swallow something too large—it can actually give them brain damage.

Octopus Tentacles

The suckers on octopus tentacles can taste whatever they touch, and will stick to just about everything, except octopus skin—presumably because it tastes like octopus skin. So they never get physically tangled up in or stuck on themselves, though they are otherwise pretty solitary and self-absorbed.

Venom

All octopuses, including the Giant Pacific, are venomous, but only one is known to be deadly to humans. And it isn’t this one; if you’re interested, it’s the blue-ringed octopus, which inhabits parts of the Indian and Pacific oceans, ranging from Japan to Australia.

Historical/Cultural References and Uses

Octopus has long been eaten as a delicacy by Asian and Mediterranean cultures, and used as effective halibut bait here in our western fisheries.

But aside from these practical considerations, this clever and mysterious creature has given rise to a multitude of myths and legends, predating the dawn of recorded history. Norway’s Kraken, Japan’s Akkorokamui, and probably ancient Greece’s Gorgon and Scylla owe their inspiration to the Giant Pacific Octopus, or perhaps one of its extinct ancestors. British pop stars have sung about them. Literary greats, like Victor Hugo and Jules Verne, have required their protagonists to battle them. And the silver screen has often been entangled in their spell. Octopuses have caught our imaginations for as long as there have been fish stories, and they will probably continue to captivate us, as long as there are fishermen around to tell of them.