Octopus are fascinating creatures. Their elusiveness; the way they undulate their bodies as they climb over rocks and coral; the kaleidoscope of colors, which they can shift in an instant; and the seeming intelligence in their eyes all make them a hit on any dive.
The Giant Pacific Octopus
The largest, and most elusive, of the cephalopods is the giant Pacific octopus. Found in the cold waters of the Pacific from the coast from Southern California to Alaska, and along the coastline of Japan, these animals live in a variety of depths ranging from shallow coastal waters to over 4,500 feet.
The giant Pacific octopus’ life expectancy is three to five years in the wild and, during that time, these animals can grow to lengths over 15 feet and weights between 22 and 110 pounds, making them the largest of the octopuses. The largest specimen ever recorded was 30 feet long and weighed over 600 pounds.
Each of the octopus’ arms can grow to be six feet long, giving the animals an arm span of 14 feet across. Each arm is lined with suction cups for gripping objects and prey items. Female octopuses possess an average of 280 suction cups per arm; the males average 270. When utilizing all eight arms, the giant Pacific octopus is capable of moving over 700 pounds.
These suction cups contain thousands of chemical receptors that are so sensitive they can detect taste by touch. This is a valuable tool while hunting, as it allows the octopus to reach into small crevices with its arms and determine whether there is a food source inside.
Arms do not make for great swimming, though, so octopuses rely on jet propulsion to move through the water column. Like a squid, an octopus will draw water into a sac in its mantle cavity. The animal rapidly expels the water through a narrow opening, pushing its body backwards. When not moving through the open water, octopuses can be found living on the sea floor, where they can use their arms for locomotion.
Octopuses have been referred to as an inside-out mollusk — unlike other mollusks, which have a soft body inside a hard shell, octopuses have a soft body on the outside and the shell works as an anchor for the cephalopod’s large head. Octopuses also differ from their clam cousins because of their sharp, flesh-piercing beak. Coupled with powerful arms, this beak allows octopuses to eat a variety of foods, including clams, crabs, scallops, shrimp, lobsters, fish, sharks and birds.
But octopuses are perhaps most famous for their camouflage abilities. An octopus’ skin holds pigmentation cells, which become activated when the animal is disturbed. Each of these cells, called chromatophores, contains three sacks of different pigmentation that are adjusted individually until the animal blends in with its background. If the danger persists, octopuses are capable of expelling a cloud of dark ink, which, in the case of the giant Pacific octopus, has been known take the shape of an octopus, providing an escape for the animal.
Giant Pacific octopuses have proven intelligent, capable of learning skills taught to them by humans, such as opening jars, playing with toys and completing mazes. These animals have also been known to interact with their human handlers, disproving the notion that only social animals are capable of intelligence. Of all the invertebrates, octopuses possess the most complex brains and are capable of forming both short- and long-term memories. EEGs of sleeping giant Pacific octopuses have revealed these animals have a REM sleep cycle and may possess the ability to dream based on demonstrated brainwave activity.
The goal of every species is successful reproduction, and the giant Pacific octopus is no exception. Sexual reproduction results in 20,000 to 100,000 eggs. After fertilization, the female octopus will forgo hunting and eating for the seven months it takes for her eggs to hatch. During this time, she will tend her nest, cleaning and aerating her eggs. After incubation, the eggs hatch, each baby octopus equipped with 14 suction cups per arm, and head into the ocean where they will spend the next several months living and feasting in the phytoplankton drift. The female octopus, having sacrificed her own health for that of her eggs, will die shortly after the last egg has hatched. The father, who does not assist in the guarding of the eggs, will have died several months after mating was complete.
The fate of a young giant Pacific octopus is fragile. After spending three months drifting amongst the phytoplankton, these animals will come to rest on the sea floor. It takes over a year for the juveniles to reach a weight of two pounds, but they grow rapidly after that milestone, gaining an average of 18 additional pounds by the time their second birthday comes around.
For the first two years of their lives, the young giant Pacific octopus faces many threats. Birds, lingcod, seals, sea otters and other octopuses have been known to feed on these nearly defenseless creatures. Humans are also a threat to young and old octopuses, as some countries consider these animals to be a delicacy. In Japan, these animals are the most common marine species hunted, with over 20,000 metric tons harvested annually.
Currently, the IUCN Red List has not evaluated the giant Pacific octopus’ conservation status, nor are they listed on any of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) appendices. While these animals are not currently endangered, they are still susceptible to global climate change, environmental degradation and introduced pollutants. Octopuses have also come under attack from fishermen after having poached the crabs found in the fishermen’s pots. And sometimes these animals are killed simply because “it’s legal and there’s lots of them down there,” as one such diver stated after killing one of these animals as part of an art project. As it stands, the total giant Pacific octopus population is unknown, though it is not believed to be in immediate danger. These intelligent, charismatic creatures play an important role in the ocean ecosystem and it is our responsibility to protect them and their habitat.
By guest author Christina Albright-Mundy