Octopuses (or octopi) are cephalopods, invertebrates that also include squid and cuttlefish. There are around 300 species found in oceans across the world, from shallow coastal waters, tide pools, seagrass and algal beds to deep-sea habitats. They are often found in rocky crevices, coral reefs or soft sediments, where they can hide and find prey. They are generally solitary and territorial creatures – they prefer to live alone and not be bothered.
Octopuses have soft bodies, bulbous heads, large eyes and eight arms lined with hundreds of suckers. Most of their neurons (nerve cells) are in their arms – nearly twice as many as in the central brain. These complex bundles of neurons act as a ‘mini-brain’ in each arm, letting them touch, smell and manipulate objects quickly and effectively.
Octopuses have blue blood because the protein haemocyanin, which carries oxygen around their body, contains copper rather than iron – as we have in our haemoglobin. This copper-based protein is more efficient at transporting oxygen in cold conditions, so it is ideal for ocean life. An octopus has not one but three hearts: two branchial hearts pump blood to the gills, where it collects oxygen and a third, systemic heart, pumps oxygenated blood around the body.
Remarkable Cognitive Abilities
With 500 million neurons – a number more typically found in vertebrates such as dogs – octopuses have the largest nervous systems among invertebrates and are considered among the most intelligent of them.3Carls-Diamante S. 2022. Where is it like to be an octopus? Frontiers in Systems Neuroscience. 16, 840022. They can exhibit remarkable cognitive abilities, such as maze-solving and observational learning. Once octopuses have solved a new problem, they retain long-term memory of the solution. They have the reputation of being remarkable escapologists and are adept at getting themselves in and out of containers. They can construct a shelter, often using a makeshift ‘door’ to protect it.
Tool use is a good indicator of the ability to learn but is relatively rare among animals and is usually associated with apes, monkeys, dolphins and some birds, such as crows and parrots. However, among invertebrates, octopuses and a few insects are known to use tools. An impressive and convincing example of tool use by octopuses came in 2009 in Indonesia, when a few veined octopus (Amphioctopus marginatus) individuals were seen collecting discarded coconut shells and carrying them across the seafloor to use as a shelter when required.4Finn JK, Tregenza T and Norman MD. 2009. Defensive tool use in a coconut-carrying octopus. Current Biology. 19 (23) R1069-70. To carry the shells, they had to use some of their arms to walk along the seafloor as if on stilts, potentially making them vulnerable to predators, but they appeared willing to accept the short-term risk for future protection.
The incredible film My Octopus Teacher on Netflix documents the life of a female wild common octopus and the filmmaker’s close relationship with her as he follows her around for nearly a year. Her daring escape from a shark is mind-bogglingly creative and her camouflages, an impressive delight. One thing is certain: octopuses are bright creatures, poorly understood by humans.
Octopus Factory Farms
Octopus aquaculture is the factory farming of octopuses and commercial sale of their meat. Aquaculture already causes huge environmental damage – commercial octopus farming will likely increase harm to local ecosystems. Furthermore, like farmed fish, octopuses have a food conversion ratio of at least three to one, meaning that they require as much as three times their weight in feed. Given the decline in global fisheries, farming a carnivorous species makes no sense and increases the threat to global food security.
To date, the majority of octopuses used for food are wild-caught but octopus fisheries are in decline, with many now overfished. Because of this, Compassion in World Farming says that “there are plans to confine these fascinating, inquisitive and sentient creatures in factory farms”.29Compassion in World Farming. 2021. Octopus farming: a recipe for disaster. Available at https://www.ciwf.org.uk/media/press-releases-statements/2021/10/octopus-farming-a-recipe-for-disaster [Accessed 10 October 2023]. According to Sentient Media, there are a number of facilities in the works that could become commercial octopus farms.30Mishler, J. 2023. Explainer: is octopus farming ethical? Available at https://sentientmedia.org/octopus-farming/ [Accessed 10 October 2023]. In 2019, it was reported that in several countries, including Spain, Italy and Australia, experimental production has begun in tanks on land, in open-ocean net pens and on ‘ranches’ where wild-caught octopuses are raised in captivity, and that attempts to farm octopuses are also underway in Latin America, China and Japan.31Jacquet J, Franks B, Godfrey-Smith P et al. 2019. The case against octopus farming. Available at https://issues.org/the-case-against-octopus-farming/ [Accessed 10 October 2023].
The farm that appears closest to production is based in the Canary Islands and could be the world’s first octopus factory farm. Grupo Nueva Pescanova’s plan came into public view in 2021 when it applied for permits to build a two-storey farm at the port of Las Palmas in Gran Canaria. They are planning a farm that could eventually provide up to 3,000 tonnes of octopus meat a year – requiring the slaughter of about one million common octopuses (Octopus vulgaris).32Kassam A. 2023. ‘A symbol of what humans shouldn’t be doing’: the new world of octopus farming. The Guardian, 25 June. Available at https://www.theguardian.com/environment/2023/jun/25/a-symbol-of-what-humans-shouldnt-be-doing-the-new-world-of-octopus-farming [Accessed 10 October 2023]. Roberto Romero Pérez, a marine biologist who oversees aquaculture at Grupo Nueva Pescanova, suggests the first batch of product – which could be between 300 and 500 tonnes of octopus meat – will probably not hit the market before 2027.
The reason most octopuses currently used for food are wild-caught is probably due to the huge difficulties associated with farming them for food – they are not very sociable and show little tolerance for other individuals. Scientists say they are particularly ill-suited to life in captivity and mass production and that it would cause them to suffer greatly due to their intelligence as well as curious, solitary and territorial nature. Philosopher Stefan Linquist of the University of Guelph in Ontario, who studied octopus behaviour, says octopuses “know that they are inside this special place, and you are outside it. All their behaviours are affected by their awareness of captivity”.33Godfrey-Smith P. 2017. The mind of an octopus. Scientific American, 1 January. Available at https://www.scientificamerican.com/article/the-mind-of-an-octopus/ [Accessed 10 October 2023]. This is probably why there are so many tales of daring escapes, like Inky, a common New Zealand octopus (Macroctopus maorum) who climbed out of his tank, crossed the aquarium floor and went down a 50-metre drainpipe to the sea and freedom.34Ainge Roy E. 2016. The great escape: Inky the octopus legs it to freedom from aquarium. The Guardian, 13 April. Available at https://www.theguardian.com/world/2016/apr/13/the-great-escape-inky-the-octopus-legs-it-to-freedom-from-new-zealand-aquarium [Accessed 10 October 2023].
