The world’s oceans harbor colossal invertebrates, and among the most fascinating are the giant cephalopods. These creatures are masters of camouflage and possess remarkable intelligence. Determining the biggest species requires separating anecdotal records from scientific measurements, leading to a complex picture of immense arm spans and substantial body masses. The search for the largest octopus reveals a competition between two deep-sea giants.
The Record Holder
The Giant Pacific Octopus (Enteroctopus dofleini) is widely recognized as the largest octopus species when considering both arm span and overall mass. Historical records describe a massive individual with an arm span reaching up to 32 feet and a total weight of 600 pounds.
While these extreme measurements represent the upper limit of what has been anecdotally reported, confirmed adult sizes are still impressive. Most mature Giant Pacific Octopuses typically weigh around 150 pounds and can stretch their arms to a diameter of up to 20 feet. One scientifically confirmed measurement documented an individual weighing 437 pounds. This species is found along the coastal areas of the North Pacific, stretching from the western coast of North America to the shores of Japan, living in rocky dens and caves.
Weight Versus Span
Defining the “biggest” octopus requires a distinction between the length of its arms and its total body mass. While the Giant Pacific Octopus holds the record for the longest arm span, the Seven-Arm Octopus (Haliphron atlanticus) presents a challenge for the title of the heaviest. The female Seven-Arm Octopus is estimated to be the most massive of all octopus species, though confirmed weights do not surpass the extreme GPO records.
The largest validated specimen of the Seven-Arm Octopus measured 9.5 feet in total length and weighed 134.5 pounds, even though the specimen was incomplete. This species is named for the fact that the male tucks one of its eight arms, a specialized reproductive arm called the hectocotylus, into a sac near its eye, giving the appearance of having only seven limbs. The Haliphron species possesses a thick, gelatinous body texture, which contributes significantly to its bulk and potential for a greater overall mass than its arm span might suggest.
Life in the Deep
These massive cephalopods live solitary lives in the cold waters of the North Pacific Ocean, often at depths that reach down to 4,900 feet. Their preferred habitat includes rocky structures and crevices, where they establish dens and hide from predators. The Giant Pacific Octopus, like its large relatives, is a predator, using its powerful arms and beak to capture and consume a varied diet.
Their primary food sources consist of crustaceans, such as crabs and shrimp, as well as bivalves like clams. They are also known to prey on various fish and occasionally small sharks, using venomous saliva to paralyze their catch. Despite their large size, the Giant Pacific Octopus has a short lifespan, typically living for only three to five years. This existence culminates in a single reproductive event, after which the female guards her eggs for many months without eating, dying shortly after they hatch.