You may have seen in the news cycle recently that a young girl saved a beached giant Pacific octopus at Bay View State Park by using her toy bucket to pour water over it until officials could come help.1 With their species in the headlines, it seems like a great time to do a deep dive on the giant Pacific octopus. These animals are adaptive, highly intelligent, resilient, and may surprise you if you haven’t given them much thought before!
Giant Pacific octopuses (Enteroctopus dofleini) are mollusks belonging to the cephalopod family and are related to squid, cuttlefish, and nautilus. They are the largest species of octopus in the world- weighing anywhere from 22-160 pounds, but average around 50 pounds.2 While you might be compelled to call their eight appendages tentacles, the distribution of their suction cups down the entire length of their limb distinguishes them as arms.3 Conversely, tentacles only have suction cups at the end of the limb.3 Giant Pacific octopuses boast over 2,100 individual suction cups per arm! Adult octopuses have arms that can range from 7 feet to oftentimes more than 13 feet. They can be found anywhere from Baja California to Alaska to Japan in deep and shallow water.2 On occasion, they may peruse tide pools for a meal but cannot live more than 30-60 minutes outside of water.1
Giant Pacific octopuses are generalist feeders who have a diet primarily comprised of crabs, shellfish, and other mollusks.2 To infiltrate the hard shells of their prey, octopuses have developed an impressive toolkit. The first is the strength of their suction cups that they leverage with incredible force to pry shells open. Difficult shells are subjected to the next method, where the octopus uses its beak to bite them open.4 The composition of secreted saliva helps to soften the shell, which can then be drilled through with their radula (analogous to a human tongue!)5. Once entry is gained to the interior of the shell, the octopus injects a paralytic toxin that dissolves the target’s soft and connective tissues allowing consumption of the contents.4
As fascinating as their feeding habits are, the hunt is even more exciting. Through the synergy of nerves, muscles, and millions of elastic cells with specialized color pigments, octopuses have one of the most complex camouflaging systems in the animal kingdom.4 Their ability to instantaneously switch colors and textures enables the octopus to blend into its background, vital for pursuing prey and eluding predators. Studies have shown that octopuses are color blind, which is baffling considering their camouflaging prowess. Many theories have been presented for how this paradox could exist, but experiments are ongoing to find a definitive answer.6
Octopuses are very patient hunters and will lay in wait for an unsuspecting victim while blending into their environment. In addition to stealth, octopuses utilize a jet propulsion system to travel quickly over short distances.2 They spend most of their time in a den to stay protected from large fish, marine mammals, and some sharks.4 They are also highly intelligent and have proven able to solve puzzles, escape enclosures, recognize people as well as being the only invertebrate that has exhibited play behavior.4 Giant Pacific octopuses maximize these strengths to survive amongst a host of dangerous predators.
The giant Pacific octopus leads a solitary life for three to five years before seeking a mate. The female selects a male and they travel to deeper waters to reproduce. The female returns to shallower waters and hangs her 17,000 – 74,000 eggs from the roof of her den like strings of grapes.2 The mother then tends to her eggs non-stop for up to six months by pumping oxygen and nutrient-rich air through the den and keeping the eggs clean. She dedicates so much of herself to her brood that she doesn’t eat for their entire development. Shortly after the young octopuses hatch, the female octopus dies.4 On the hatchling’s first day, they have all eight arms and around 14 tiny suction cups per arm.4 Without a fully developed array of defensive strategies, mortality during the larval stage is high. Octopuses are also fished for many different cuisines. Despite the challenges of surviving, giant Pacific octopuses are not endangered and have a good outlook on staying that way!
[Author’s Note: If you are as enchanted by the giant Pacific octopus or even octopuses in general as I am, I highly recommend watching My Octopus Teacher, which won an Academy Award for Best Documentary Feature in 2021! You can further indulge in Remarkably Bright Creatures, a novel by Shelby Van Pelt that explores the relationship between an aquarium janitor and it’s resident giant Pacific octopus]
References:
- Wakayama, Brady. “Giant Pacific Octopus Rescue in Mount Vernon Caught on Camera.” King 5 News. MSNBC, March 22, 2023. https://www.king5.com/article/life/animals/giant-pacific-octopus-rescue-mount-vernon/281-4233400d-83c2-499b-9c0f-13c3bd8f399d.
- AZA Aquatic Invertebrate Taxon Advisory Group (AITAG). Giant Pacific Octopus (Enteroctopus dofleini) Care Manual. Association of Zoos and Aquariums, Silver Spring, MD. 2014. https://assets.speakcdn.com/assets/2332/giant_pacific_octopus_care_manual_final_9514.pdf
- “Giant Pacific Octopus.” Ocean Conservancy. Accessed March 31, 2023, from https://oceanconservancy.org/wildlife-factsheet/giant-pacific-octopus/
- “Giant Pacific Octopus.” Monterey Bay Aquarium. Accessed April 2, 2023. https://www.montereybayaquarium.org/animals/animals-a-to-z/giant-pacific-octopus.
- Scheel, Carolin et al. “Not just scratching the surface: distinct radular motion patterns in Mollusca.” Biology openvol. 9(10). Oct. 21, 2020, doi:10.1242/bio.055699
- Stubbs, Alexander L., and Christopher W. Stubbs. “Spectral Discrimination in Color Blind Animals via Chromatic Aberration and Pupil Shape.” Proceedings of the National Academy of Sciences 113, no. 29 (2016): 8206–11. https://doi.org/10.1073/pnas.1524578113.
Photo captions:
- Photo by Oleksandr Sushkoon Unsplash (image of giant Pacific octopus gliding through a reef)
- Photo by Sigmundon Unsplash (image of giant Pacific octopus from profile view)
© Rachel Davey, April 2023