For a couple of years, Inky the octopus was a popular attraction at the National Aquarium of New Zealand in Napier. Then, one morning in 2016, his tank was empty. Inky had made a daring break for freedom.
Aquarium staff soon discovered that a small gap had been left at the top of the tank following maintenance work. Inky, it seems, had squeezed through, slithered across the floor and then slipped into a drainage pipe that led to the sea. His daring escape inspired worldwide media interest and several children’s books.
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Inky’s exploits were not out of the ordinary, though. Members of the order Octopoda are renowned for their problem-solving abilities and contortion acts, navigating mazes, opening jars and squeezing through the most unlikely of gaps.
At a marine educational centre in New Zealand’s capital, Wellington, an octopus was caught sneaking into another tank at night to pinch crabs – a cunning ploy of which fishers in south-west England are only too aware.
Permit conditions issued by the Devon and Severn Inshore Fisheries and Conservation Authority state that pots used for crab and lobster fishing must be installed with a gap at least 84mm wide and 46mm high to allow undersized or immature shellfish to escape. That edict has lately created a problem.
In early 2025, fishers began finding an increasing number of pots either empty or containing the remains of predated crustaceans.
On one occasion, a suspected culprit was also discovered inside: a common octopus (Octopus vulgaris) that, it seems, had squeezed through that gap – barely larger than a credit card – then, having overindulged in crab and lobster, was too portly to get back out.
How big is a common octopus?
An adult can reach 1m long and up to 9kg.
Is it dangerous to humans?
The common octopus is venomous but rarely attacks people. A bite would be painful, but a greater threat would be subsequent infection.
How long do octopuses live?
Typically, one to two years; longer if kept in captivity without mating. Octopuses are semelparous: each breeds once, then dies.
How many hearts does an octopus have?
Three. Two peripheral hearts are positioned by the gills to pump oxygenated blood, while a central, two-chambered heart distributes it all around the body.
What do octopuses eat?
Octopus larvae eat plankton before they move to the seabed, when their diet changes to include crustaceans and molluscs. Crabs are the favourite prey of adults.
Which predators feed on octopus?
Large fish such as sharks and conger eels, dolphins, seals and some marine birds.
Can an octopus change its colour?
Yes! It has pigment-filled sacs called chromatophores, which enable it to adjust its colour as a form of camouflage or for communication.
How do they breathe?
Octopuses have gills through which they absorb oxygen from the water. They also absorb some oxygen through the skin.
How does an octopus move?
It propels itself forward by forcing water through the siphon, with its limbs trailing behind. Octopuses are weak swimmers.
How common are they?
The IUCN classifies Octopus vulgaris as of ‘Least Concern’, although it remains uncommon in British waters.
How do octopuses breed?
To mate, a male octopus uses his arms to grip the female, and uses a specialised arm called a hectocotylus to transfer sperm into her mantle. She then finds a rocky crevice or cavity, which she cleans – and sometimes decorates with shells and small stones – before laying clusters of up to 500,000 small white eggs.
There she broods her clutch, gently circulating water around the eggs to maintain oxygen levels. They hatch after four to eight weeks, depending on the temperature of the water. The female remains here throughout this period, defending the eggs from potential predators but not eating anything herself.
Importantly, each octopus mates only once in its life, after which the hormonal shift involved prompts the optic gland to trigger a rapid process of senescence (biological ageing), and it dies not long afterwards.
Eggs in warmer seas hatch after about a month, whereas in cooler waters the female may die before her young emerge, potentially leaving underdeveloped eggs or an unprotected nest.
Octopus larvae – only 3mm long at hatching, looking like tiny versions of adults – drift on the water column and feed on other larvae or brine shrimp before settling on the seabed to begin a benthic existence. Growth is then swift, with juvenile octopuses increasing their body weight by as much as 5% in a day.
Do octopuses have skeletons?
An invertebrate, the octopus lacks a skeleton but has a beak formed from chitin – the same substance in the exoskeletons of arthropods and crustaceans. It uses that parrot-like beak to crack or drill into the shells of clams, lobsters and especially crabs.
How do octopuses hunt?
Tucked out of sight, an octopus lies in wait to ambush passing prey. You might identify a favoured hiding place by spotting a pile of discarded crab shells, sometimes known as a midden.
Such debris is sometimes stacked around the entrance to an octopus den as a defensive wall – another indicator of this creature’s intelligence, which is particularly remarkable given its short lifespan.
Learned behaviours often develop through trial and error, or a combination of innate instinct and blind luck. A common octopus rarely lives beyond two years – not much time to learn from its mistakes.
How intelligent are octopuses?
The brain of an octopus is the largest of all invertebrates relative to its body size. It also has 500,000 or so neurons – a similar number to a dog’s – largely clustered in its eight arms, effectively providing each with a mini-brain.
That enables each suckered appendage to process sensory information independently, to rapidly and dextrously search cracks or holes for food or a safe hiding place.
A 2011 study led by Tamar Gutnick of the Hebrew University of Jerusalem found that a common octopus could negotiate a three-choice maze with a single arm. The maze was transparent, so each subject (seven were tested) was able to see the target. Completion of the task required the octopus to “associate a visual cue with their own voluntary motor actions”.
It seems that they are able to recognise individual people, too. Another New Zealand octopus – this one at the University of Otago in Dunedin – took to squirting water at one particular staff member whenever they passed its tank. Was it a sign of affection or aggression?
Another octopus in the same facility learned that squirting at lightbulbs could trip the fuse and switch out the lights. We have to be wary of anthropomorphic interpretations of such behaviour, but evidence of impressive cognitive ability has long fascinated scientists and inspired artists, writers and filmmakers.
Can octopuses regenerate?
The Oscar-winning 2020 film My Octopus Teacher, directed by Pippa Ehrlich and James Reed, follows the relationship between diver Craig Foster and one common octopus that he befriends in a kelp-bed on the Atlantic coast of South Africa. During the narrative, the octopus loses an arm to a striped catshark but re-grows the limb over the course of three months.
This regenerative ability is among several remarkable biological attributes of the common octopus.
How do octopuses defend themselves from predators?
Its ability to produce and eject ink – for which Inky the octopus was of course named – is a useful defence mechanism deployed in encounters with predators. This ink, coloured black by melanin, is stored in a sac connected to the siphon – a muscular, multi-purpose tube that aids breathing, waste discharge, propulsion and, in expelling ink, defence.
Are octopuses good swimmers?
Octopuses are not strong swimmers so, by squirting a black cloud of ink into the sea, aim to disorientate an attacker and escape. This evasive behaviour is shared by other cephalopods, such as squid
and cuttlefish.
Can you eat octopus?
These cephalopods are all edible, if cleaned and prepared correctly, yet are not widely used in British cuisine. However, calamari rings – typically slices of squid, battered and deep-fried – are popular here, perhaps because of the cooking style and their inoffensive ‘onion ring’ appearance.
These creatures are all eaten elsewhere in Europe. Common octopus is popular in many Mediterranean dishes, and the species remains widespread across the region, being abundant in some areas. It prefers shallow coastal habitat, with rocky substrate to hide in and warm water in which eggs develop quickly.
Morocco is the world’s leading exporter of octopus, a trade worth around $612 million (about £500m at the time) in 2023 – equating to around 40–45,000 tonnes.
Much of it is sold into the EU, where demand is strong. When one Cornish trawler landed £142,000 worth of octopus in June 2025, the vast majority was sold into France, Spain and Germany.
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