GIANT PACIFIC OCTOPUS

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THE GIANT PACIFIC OCTOPUS

BY JOHN M. REGAN

Our Northwest shoreline is home to one of the most fascinating creatures on God’s earth – the Giant Pacific Octopus. Of the 300 hundred or so species of octopods that inhabit the world’s oceans the biggest of them all is our very own Octopus dofleini (sometimes also Enteroctopus dofleini). Yes, we share the big guy with other shorelines of the North Pacific from California to Asia, but like the great orcas this octopus likes the cold waters of the Northwest.

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Giant Pacific Octopus by John M. Regan

Several viewpoints of the Giant Pacific Octopus from the Seattle Aquarium. This fellow stretched out to about ten feet and was in fine form the day I visited. The typical color of a relaxed specimen is the reddish hue seen above. Their easy glide along the ocean floor is supplemented by occasional burst of water jet propulsion as seen in the middle photo. Hidden away underneath the mantle is the beak. Reports of bites are oft repeated, but instances are actually rare.

So how big are they? Despite all the fuss about the size of this octopus, reports of actual measurements vary widely. The largest ever recorded according to the National Geographic Field Guide stretched ten feet from tentacle tip to tentacle tip, but there are reliable reports of 16 feet long, 600 pounds specimens. Some sources claim thirty feet. The disparity is not unexpected. Accurately measuring an animal like this is a difficult task to say the least, and sources don’t always state how the measure was made. Tentacle to tentacle or mantle (head) to tentacle tip? Was the animal dead? Dried in the sun? An exercise like this in the wild is just about impossible. Twenty feet from tentacle tip to tentacle is probably reliable as an average, although there are surely larger specimens out there.

Whatever the true limits of this creature’s dimensions are it is a remarkable animal by any standard. Imagine the reaction of a diver first confronted with an eight limbed monster three times his size, fins included. That would be an event to remember. And the intrigues don’t stop there. What other animal besides an octopus has three hearts, no internal or external skeleton, a sophisticated brain, complex behaviors, a birdlike beak hidden inside its body, and eyesight to rival any mammal? What other animal can instantly vanish? Or possesses the ability to pour its body like water through the tiniest cracks and crevices? There may be some comic book superhero claiming these talents, but in the real world only an octopus actually possesses such incredible attributes.

Our home grown giant, like all members of the octopus family, belongs to the phylum of animals called Mollusks: clams, oysters, snails, slugs, and squids. Narrowing this down we come to the class called Cephalopods where we find octopus and squids along with cuttlefish and the odd little nautilus, (the only cephalopod, by the way, with a fully developed external shell). Characterized by the biologically popular term of “bilateral symmetry,” cephalopods possess a number of interesting qualities. Of all the invertebrates on earth, and there is an astounding number, the octopus and squids are far and away the most intelligent. They also have unusually keen eyesight, not something normally associated with invertebrates. They are the largest invertebrates, too, and are strictly inhabitants of the ocean. The octopus has now claimed its own order – the appropriately named Octopods.

Giant Pacific Octopus by John M. Regan

The photo on the far left shows the giant bulbous head of the octopus and an idea of the malleable skin texture that is a component of the animal's ability to suddenly vanish. The tentacles and suckers are the key components of survival for any octopus and the Giant Pacific has the record holders.

Octopuses differentiate themselves from their squid cousins in a number of ways. The octopus body, besides the tentacles, is rounded and globular, giving then the head that appears so outsized. The spear shaped squids are consequently faster, and rely primarily on water jets for movement. Octopods cannot equal the water jet mastery of squids, but their tentacles are marvelously adapted for terrain locomotion. An octopus swiftly and gracefully glides along rocky shores and sea bottoms by pulling forward with its sucker filled arms. They are even capable of travelling while out of the water, an exasperating talent well known to anyone who has kept an octopus in captivity. And speaking of tentacles there is a distinct difference here. Squids have ten arms, eight of which tend to be short and stubby and two are considerably longer. Squid only have true suckers on these long tentacles. Octopuses have eight tentacles, all generously graced with suckers.

Although the majority of us will only see our biggest octopus in a public aquarium like the Oregon Coast or Seattle Aquarium do not despair of ever seeing one in its natural habitat even without scuba gear or training. They dwell in very deep water nearly out to the two thousand feet level but are occasionally found in intertidal environs as well. What a wonder it would be to find this spectacular animal hiding in a tide pool. This would not be an adult specimen, of course, but it would be a memorable zoological event just the same. Don’t mistake your intertidal discovery for our other, much smaller, octopod resident – the Red Octopus, Octopus rubescens.

The giant octopus begins life in the same manner as all octopods – a tiny egg that is part of a huge cluster carefully guarded by mom in a rock crevice or some similar cave like home. The egg membrane is gelatinous but hardens upon contact with sea water and provides a protective cover. The egg contains a copious amount of yolk from which the little embryo develops. For the next six and a half months the mother octopus guards and cleans here babies tirelessly. She does not eat or leave the den and constantly maintains a gentle stream of water over them to aerate and keep them free of bacteria or other infectious agents. The gallant effort is made all the more admirable even to our human eyes because the effort literally costs the mother octopus her life. Nature has unfortunately allotted just three to five years of life for octopus; a tragically short existence for such an intelligent creature.

What pops out of the egg is called a paralarvae but it is pretty much a miniature of an adult octopus, replete with the oversized mantle and elongated arms. The tiny creatures are on their own in the form they will retain throughout life. It does not take a lot of imagination to conjure up the image of what a beebee sized predator eats. It must obviously be smaller than the predator, so another small invertebrate such as a tiny copepod would fit the bill. At this very fragile point in life the baby octopus is only a couple of millimeters long and actually does not swim, it floats along like plankton at the water surface or some sort of debris and tends to eat anything that comes along alive or not.

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This incredibly interesting part of the animal’s life has not been well documented, but there is little doubt that it is the most dangerous in the life of any octopus. If it survives and outgrows this floating existence it begins life as a true octopus – moving on its own and actively seeking out prey that becomes progressively larger in accordance with the animals own growth. But the IF in the previous statement is a huge IF. Of the thousands of eggs (estimates vary from 35,000 to 100,000) laid by the mother octopus only about one percent will survive. How many more go on to adulthood is probably a lot less; accurate numbers are not known. Whatever the case, those are not good odds. The next time you are lucky enough to see large octopus pause and think about those odds and the incredible luck and toughness the animal had to possess to make it beyond infancy.

Once beyond this stage its home can no longer be among the floating scrum and flotsam at the ocean surface. To get be a real octopus the animal must descend to the ocean floor and start life. It moves into adulthood and no longer relies on plankton and copepods. The adult diet consists of crabs, shrimp, clams, oysters, scallops, and other octopuses as well. It will likely take anything it can catch. Fully grown the giant octopus will even attack and eat sharks – that’s a long way from the pea sized, nearly helpless drifter that began life such a short time ago.

The giant pacific octopus attacks prey with a speed that is surprising for such a large animal. At first blush the creature looks incredibly clumsy with its oversized, ungainly spheroid head that looks more like a water filled balloon than a head. That spheroid shape, however, is an adaptation that allows very fluid movement in water. Add to this a pair of powerful water jets and you have the formula for rapid swimming. But the real trick to the giant octopus’s hunting technique lies mainly in its most obvious feature – the tentacles. Most of the prey of the giant is slow or downright sessile. Shrimp and crabs are not the fastest creatures in the ocean. The locomotion of scallops and clams is peculiar to say the least and they are not known as the cheetahs of the sea either. For this kind of prey the octopus generally sneaks up and angles itself within range. At the critical moment the eight legged attacker violently pulls forward with tentacles attached to the substrate and snares the victim with a suckered grasp from its free arms. Fish are caught in similar style; the only difference is that the octopus uses an ambush technique.

Once caught the method of kill is always the same. Octopuses have a parrot like beak hidden in the center of their mantle. The beak of the Pacific Giant looks exactly like that of a large parrot. It is not something you’d relish being bitten by, but added to this is a poison that serves to subdue prey even further. According to Dave Cowles a researcher associated with the University of Washington, the beak is used to inject venom in hard shelled prey after a hole is first bored into the victim by radula. Presumably the radula is exposed and extruded when the beak is opened.

The Giant Pacific Octopus is not without its own share of enemies, however. Seals, Sea Otters, Sperm Whales, and man all find the big octopod to be a fine addition to the palate. But the octopus’ ability to squeeze into the most unlikely crevice coupled with its extra ordinary intelligence and ability to suddenly vanish does make it an easy target. A reddish brown color when relaxed the octopus can instantly change color and skin texture to match its surroundings. The transformation is startlingly quick.

By the way, if you do have the great good fortune to come across a Giant pacific Octopus large or small – don’t handle the creature. Octopuses secrete a mucus covering that protects them from outside infections. Handling them, especially with gloves, rubs this covering off and leaves them vulnerable to disease. Remember that hidden beak, too. You just might get bitten.

References:

Whelks to Whales by Rick Harbo

Seashore Life of Puget Sound by Eugen N. Kozloff

Northwest Shore Dives, 3^rd Edition, by Stephen Fischnaller

National Audubon Society Field Guide to Seashore Creatures, 2009

Internet References:

Royal BC Museum: http://www.royalbcmuseum.bc.ca/School_Programs/octopus/index-part2.html

Dave Cowles Web Page:

http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Mollusca/Cephalopoda/Enteroctopus_dofleini.html

Wash D.C. National Zoo:

http://nationalzoo.si.edu/Animals/Invertebrates/Facts/cephalopods/FactSheets/Pacificoctopus.cfm

National Geographic: