Giant Pacific Octopus, Enteroctopus dofleini
The giant Pacific octopus (Enteroctopus dofleini), also known as the North Pacific giant octopus, is native to the North Pacific. It prefers to live at depths of 215 feet, but can be found in more shallow waters. It is thought to be the largest species of octopus with the largest specimen weighing 156.5 pounds, although the seven-arm octopus is a close contender with one specimen weighing 134 pounds.
The giant Pacific octopus can reach an average weight of thirty-three pounds with an arm span reaching fourteen feet. Although not completely reliable, one individual was recorded weighing 600 pounds with an arm span of thirty feet. The mantle, or body, of this octopus contains the majority of its vital organs and is shaped like sphere. As is typical to octopus species, the giant Pacific octopus can change the color of its skin by expanding or contracting granules located within its cells that contain the pigments that control skin color.
Although the giant Pacific octopus is large, it has a short lifespan reaching only three to five years. In order to prolong the species, it can lay up to 100,000 eggs, which the female takes full responsibility of caring for after the male implants the sperm packet inside of them and dies. The mothers may wait to place the eggs on the ceiling of a den, after which they will vigilantly guard the eggs until they hatch, and then die. Reproduction occurs only once within the octopus’ lifetime. Young octopuses are born as small as a grain of rice, and only a small percentage will live to adulthood.
The diet of the giant Pacific octopus consists of scallops, crabs, fish, clams, abalone, and shrimp. The small creatures are caught by the suckers on the tentacles of the octopus, and then crushed by its strong beak. In captivity, it has been known to catch the spiny dogfish, a small shark that can reach a length of four feet. This behavior has also been recorded in wild individuals, suggesting that small sharks may form a portion of its diet in the wild. It was reported by media outlets that Ginger Morneau captured photographs of one individual capturing a seagull on the surface of the ocean in 2012, suggesting that it may eat any type of protein available.
Common predators of the giant Pacific octopus include sea otters, sperm whales, and harbor seals, with all three species relying on it as a major food source. The Pacific sleep shark will consume this octopus as well. In the United States, this octopus species is commercially fished. Little is known about its population numbers because it is so elusive, so it is not possible to place it on the IUCN Red List or place it under the protection of CITES as of yet.
Although it is often not the main target of fishermen in Alaska, an area of its range, the giant Pacific octopus can become caught in nets. These are most often found in pots containing Pacific cod, and are thrown back to sea. However, some octopuses are kept as bait or sold for human ingestion. It is kept as bait because even after being cut off, the tentacles still move.
The NOAA has dedicated a team of scientists to studying species caught by Alaskan fishermen, including those caught indirectly like the giant Pacific octopus. It is important to regulate the number of captures that fisherman can make, but because so little is known about the giant Pacific octopus, the NOAA must learn more in order to help protect it.
In order to learn more about the giant Pacific octopus, the NOAA has teamed up with the University of Alaska to find more ways to capture and tag it. One major aspect of these studies is the creation of a fishing technique that is meant specifically for this octopus, because it is so rarely caught in fishing nets. Scientists have come with manmade dens that the octopus that appeal to this octopus’ love for hiding. In one of these experiments, funded by North Pacific Research Board (NPRB Project 906), different pots and variously shaped items were used to see which makeshift “home” would gather the most octopuses.
Reid Brewer a biologist from the University of Fairbanks Alaska, conducts research pertaining to the growth of the giant Pacific octopus, working off of a commercial fishing vessel. Brewer places a few colored plastic dots under the skin of each octopus, taking care to give each one a distinct pattern. After placing these, Brewer weighs the octopus and records the time and date, repeating the weighing process when each octopus is caught again. The studies conducted by Brewer will help researchers understand the lifespan of the octopi, the population numbers in Alaska, and where the octopuses travel throughout the year.
The NOAA is also conducting studies on the reproductive habits of the giant Pacific octopus, collaborating with the Kodiak Laboratory at the AFCS. The specimens caught while researching a good fishing methods are also used in these laboratories. The scientists determine how close the octopi are to reproducing by measuring them, recording how many eggs are produced, and studying the conditions of the reproductive organs throughout the year. This information allows the research team to understand which time of year is optimum for reproduction.
The octopus is able to squeeze through any space that its beak can fit through, and its body is nearly ninety percent muscle. Every species of octopus is able to produce venom, although most species are not harmful to humans. One species that is highly dangerous is the blue-ringed octopus, found in Australia. For more fun facts and a video produced by the NOAA, visit http://www.nmfs.noaa.gov/stories/2012/08/08_17_2012_octopus_video.html.
Image Caption: A Pacific Giant Octopus (Enteroctopus dolfeini) was observed off Point Piños, California, in August 2004 at a depth of 65 meters during sanctuary sea floor monitoring surveys using the Delta submersible. Credit: NOAA/R. N. Lea/Wikipedia