Enteroctopus dofleini

The giant Pacific octopus (Enteroctopus dofleini, formerly also Octopus apollyon), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus Enteroctopus. Its spatial distribution includes the coastal North Pacific, along California, Oregon, Washington, British Columbia, Alaska, Russia, Japan, and Korean Peninsula. It can be found from the intertidal zone down to 2,000 m (6,600 ft), and is best adapted to cold, oxygen-rich water. It is the largest octopus species, based on a scientific record of a 71-kg (156-lb) individual weighed live. All cephalopods have bilateral symmetry, a shell gland, a mantle, and a well-developed head with sucker-covered arms. The octopus has eight arms, each of which has two rows of suckers. Many of the suckers are lined with papillae or hooks for adhesion. The web between the arms can be expanded to form a parachute-like structure to capture prey. In the center of the arms is a mouth, containing beak and radula (toothed-tongue). Cephalopods have a paralytic and digestive toxin in two salivary glands to aid in opening prey. Water is pulled into the mantle and over gills or lamellae for oxygen uptake, and can be ejected forcefully through the siphon for jet propulsion. They are able to reach speeds up to 40 km/h (25 mph) for short sprints. They tend to use their arms as legs, and slowly crawl along the bottom. The siphon is also used to expel ink for escaping predators. The entire body of the octopus is compressible, so they are able to fit through any opening slightly bigger than the size of their beaks (the only hard part of their bodies). Their arms are muscular hydrostats, which lengthen, contract, and contort. Octopuses are poikilothermic or cool-blooded, and have three hearts and blue, copper-based blood. The mantle of the octopus is spherical in shape and contains most of the animal's major organs. By contracting or expanding tiny pigment-containing sacs within cells known as chromatophores, an octopus can change the color of its skin, giving it the ability to blend into the environment. Subcategories of chromatophores include iridophores (reflective platelets) and leucophores (refractive platelets). Octopuses are also able to alter their skin texture, providing even better camouflage. Dermal muscles in the octopus's skin can create a heavily textured look through papillation, or cause skin to appear smooth. All of these abilities are under nervous system control. E. dofleini is distinguished from other species by its large size. Adults usually weigh around 15 kg (33 lb), with an arm span up to 4.3 m (14 ft). The larger individuals have been measured at 50 kg (110 lb) and have a radial span of 6 m (20 ft) American zoologist G.H. Parker found that the largest suckers on a giant Pacific octopus are about 6.4 cm (2.5 in) and can support 16 kg (35 lb) each. The alternative contender for the largest species of octopus is the seven-arm octopus (Haliphron atlanticus) based on a 61-kg (134-lb) incomplete carcass estimated to have a live mass of 75 kg (165 lb). However, a number of questionable size records would suggest E. dofleini is the largest of all octopus species by a considerable margin, including a report of one up to 272 kg (600 lb) in weight with a 9-m (30-ft) arm span. Guinness World Records lists the biggest as 136 kg (300 lb) with an arm span of 9.8 m (32 ft). A UN catalog of octopuses sizes E. dofleini at 180 kg (396 lb) with an arm length of 3 m (9.8 ft). E. dofleini preys upon shrimp, crabs, scallop, abalone, cockles, snails, clams, lobsters, fish, and other octopuses. Food is procured with its suckers and then bitten using its tough 'beak' of chitin. It has also been observed to catch spiny dogfish (Squalus acanthias) up to 1.2 m (4 ft) in length while in captivity. Additionally, consumed carcasses of this same shark species have been found in giant Pacific octopus middens in the wild, providing strong evidence of these octopuses preying on small sharks in their natural habitat. In May 2012, amateur photographer Ginger Morneau was widely reported to have photographed a wild giant Pacific octopus attacking and drowning a seagull, which would demonstrate the species is not above eating any available source of food within its size range, even birds. Scavengers and other organisms often attempt to eat octopus eggs, even when the female is present to protect them. Giant Pacific octopus paralarvae are preyed upon by many other zooplankton and filter feeders. Marine mammals, such as harbor seals, sea otters, and sperm whales depend upon the giant Pacific octopus as a source of food. Pacific sleeper sharks are also confirmed predators of this species. In addition, the octopus (along with cuttlefish and squid) are major sources of protein for human consumption. About 3.3 million tons are commercially fished, worth $6 billion annually. Over thousands of years, humans have caught them using lures, spears, pot traps, nets, and bare hands. The octopus is parasitized by Dicyemodeca anthinocephalum, which lives in their renal appendages. The giant Pacific octopus is considered to be long-lived compared to other species, with lifespans typically 3–5 years in the wild. Many other octopuses go through a lifespan in one year, from egg to end of life. To make up for its relatively short lifespan, the octopus is extremely prolific. It can lay between 120,000 and 400,000 eggs which are intensively cared for by the females. The female stops eating during this care and her life ends soon after the eggs hatch. Eggs are coated in chorion, and the female attaches the eggs to a hard surface. She continuously blows water over the eggs, and grooms them to remove algae and other growths. Eggs hatch in about 6 months. Hatchlings are about the size of a grain of rice, and very few survive to adulthood. Their growth rate is incredibly high. Starting from ​3⁄100ths of a gram and growing to 20–40 kg (44–88 lb) at adulthood, is around 0.9% of growth a day. Because they are cool-blooded, they are able to convert most of consumed energy into body mass, respiration, activity, and reproduction.