15 Astonishing Octopus Facts About These Intelligent Invertebrates

Welcome to the wonderful world of octopuses. Dive in as we explore various octopus facts that shed light on these remarkable creatures. 

With their unusual features, impressive intellect, and remarkable adaptability, these eight-limbed creatures embody the wonders of marine life. Similarly, these animals are some of the sea’s most intelligent and versatile creatures, possessing unique abilities and behaviors that distinguish them from other marine species.

Read on to learn about their extraordinary physical features and role in the marine ecosystem. We also explore the conservation efforts that aim to preserve them for future generations. 

Want to read more about what people have to say about these fascinating eight-legged creatures? Check out our octopus quotes!

15 Surprising Facts About Octopuses

Octopus swimming in blue water
Photo: iStock

1. Octopuses can use tools and solve problems 

Octopuses, or octopi, are incredibly intelligent animals with large brains and advanced cognitive capabilities5. They are also naturally curious creatures who love exploring new environments and objects.

Demonstrating their intelligence, they can even solve puzzles by learning from observation. Their problem-solving skills enable them to adapt to various situations, raising their chances of survival. 

Besides problem-solving, octopuses can use tools, employ foresight, and remember things. For example, they can protect themselves with coconut shells and manipulate objects with their tentacles. 

Another fun fact is their ability to recognize individual humans. Their ability to remember stuff and identify individuals sets octopuses apart from other animals, making them some of the world’s most intelligent invertebrates.

Related read: Is It Octopi Or Octopuses? What is the Correct Plural of Octopus?

2. There are around 300 octopus species in the world

giant Pacific octopus
A giant Pacific octopus. Photo: iStock

The order of Cephalopods, specifically Octopoda, showcases remarkable diversity, boasting 300 unique octopus species, such as the familiar common octopus (octopus vulgaris). These unique ocean creatures, distinguished by their bulbous heads and eight arms, inhabit a range of environments, from shallow tide pools and colorful coral reefs to the chilly, mysterious depths of the deep sea.

For example, the giant Pacific octopus, Enteroctopus dofleini, is the largest known octopus species. These large octopuses live in the North Pacific Ocean, stretching from Japan to Southern California. Some individuals of this species can reach an astounding 150 lbs with tentacles spanning up to 30 feet. 

On the other hand, the small but deadly blue-ringed octopus, from the genus Hapalochlaena, lives in the Pacific and Indian Oceans, around Australia and Japan. When threatened, the bright blue rings on the octopus’ body glow; their bite is also fatal to humans if not treated immediately. 

While the deep sea octopus resides in the formidable depths of the ocean, adapting to harsh environments and utilizing its bioluminescent abilities to navigate and communicate, the coconut octopus displays a unique resourcefulness closer to the shallow coastal waters. This talented species uses two halves of a discarded coconut shell to create an ingenious portable shelter.

3. Octopuses have three hearts 

What makes octopuses unique are their three hearts, working together to pump blood filled with oxygen and remove waste from their body.

Two of these, called branchial hearts, pump oxygen-free blood through their gills, letting the blood absorb oxygen from the water. When the blood has enough oxygen, the third heart, or systemic heart, pumps it throughout the body. This cardiac arrangement helps the octopus sustain high metabolic rates, which allows them to live an active lifestyle.

Moreover, the copper-rich protein hemocyanin carries oxygen in the octopus’ bloodstream. This protein perfectly suits deep-sea octopuses because it can transport oxygen in cold, low-oxygen environments. 

Additionally, the triple-heart system allows octopuses to expend a lot of energy in brief spurts without running out of oxygen, like hunting or swimming away from predators.

4. They have nine brains

Octopuses are known to have nine brains! In addition to the central brain, each of their eight arms possesses a mini-brain. Octopus neurons, the building blocks of their intricate nervous system, are distributed between their central and eight peripheral brains, enabling their arms to perform complex tasks independently.

5. Octopuses have blue blood

The hemocyanin mentioned above also gives octopuses blue blood; humans and other vertebrates rely on iron-based hemoglobin to transport oxygen, hence red blood. Unlike hemoglobin, hemocyanin dissolves in the blood plasma instead of being contained in blood cells. 

Besides turning their blood blue, hemocyanin helps octopuses adapt to habitats like colder waters. Its ability to bind with oxygen improves in colder environments, enabling the octopus to survive in such locations.

Arthropods and mollusks also use hemocyanin, indicating a shared evolutionary history with octopuses. While hemocyanin doesn’t bind to oxygen as efficiently, its high concentration in octopus blood compensates. 

6. Octopuses can change color and texture

A brown octopus in camouflage against a rocky sea bed
A brown octopus in camouflage against a rocky sea bed. Photo by Vlad Tchompalov on Unsplash

More fun octopus facts: an octopus can change its colors and skin textures, letting them blend into its surroundings. They have specialized skin cells called chromatophores, containing pigments that can expand or contract on command6.

Similarly, they have other skin cells called leucophores and iridophores that can reflect and scatter light. As a result, octopuses can change into various colors and patterns. Meanwhile, muscular hydrostrats help them mimic certain textures. 

Because of this ability, octopi, like the mimic octopus, can hide from predators and prey. They can also communicate with their peers. Octopuses can also reflect the look of rocks, corals, and other surfaces by simulating bumps and ridges on their body.

An octopus’s advanced nervous system allows them to change color and texture simultaneously. For example, the mimic octopus can even impersonate other marine animals to attract prey or repel predators. Despite being colorblind, most octopuses also use light intensity and contrast to help them adapt to their surroundings. 

7. Octopuses release ink clouds that can confuse predators 

The octopus defends itself against threats by releasing ink clouds through special ink sacs. An octopus’ ink is a dark substance rich in pigments expelled through its siphon, a tube-like feature that helps the animal move around. When octopi squirt ink, it distracts and confuses predators, giving them a chance to escape.

Likewise, the inky fluid contains the chemicals tyrosinase and dopamine, which can disorient predators. Tyrosinase inhibits their sense of smell, while dopamine affects their behavior and movement.

8. Octopuses can regenerate lost limbs within months 

Their ability to regenerate helps octopuses survive injuries otherwise lethal to other creatures. When an octopus loses a tentacle, a complex biological process begins; within only a few months, the process completes and produces an entirely regrown limb.

The process begins with healing the wounds, where an octopus fixes a layer of skin over the injury. While it heals, undifferentiated "blastema" cells gather on the injury site. These cells become the foundation for the new limb. Slowly, the cells turn into various tissues, constructing a new appendage for the octopus in stages4

Moreover, the new limb retains the octopus’ remarkable abilities, like changing color or grasping objects with its suckers. 

9. Octopuses are mostly solitary

brown octopus against dark blue water
Photo by Mohamed Ahsan on Unsplash

Octopuses generally live an independent lifestyle, helping them avoid competition for resources and becoming food for large marine predators. Since octopuses have a relatively short lifespan, they must focus on getting food and avoiding danger so that they can reproduce. 

Mating season is when generally solitary octopuses gather. Octopuses use chemical cues in the water to find a mate, following the signals to find each other.

When an octopus discovers a suitable mate, it begins a complex mating ritual requiring the male to use its specialized arm called a hectocotylus2. However, this intricate reproductive process entails significant risks.

For example, males can be attacked or even eaten by the females after mating. On the other hand, females often die shortly after their eggs hatch, after devoting their lives to guarding and nurturing them. 

10. Octopuses eat crabs, shrimp, fish, and other octopuses

Belonging to the squid, cuttlefish, and nautilus family, octopuses eat crabs, shrimp, clams, snails, and even fellow octopuses, depending on the species and habitat. For example, octopuses in rocky reefs feed on crustaceans, while open-water octopuses tend to eat more fish.

During a hunt, most octopus species deploy different strategies; they ambush their targets, stalk them, or lure them into their clutches.

Octopuses typically drop down on their prey, catching them with their strong tentacles, hundreds of suckers, and thousands of chemical receptors. Furthermore, an octopus has a parrot-like beak, and a tongue-like feature called the radula that can break hard shells, inject venom, and scrape out the meat.

Their diverse diets make octopuses crucial predators in marine ecosystems. For example, the giant Pacific octopus catches crabs, while the Atlantic pygmy octopus eats tiny crustaceans and mollusks. 

11. Female octopuses often die after their eggs hatch

Female octopuses protect their offspring unwaveringly, devoting their lives to their safety. When a female lays thousands of eggs, it takes them to a secluded area and attaches them to a hard surface. Depending on the species, a female octopus’s incubation period lasts weeks to months, and she watches over her young tirelessly.

The devoted mother blows water over the eggs, giving them adequate oxygen and cleaning them from debris and parasites. However, this vigilance comes with a price. While watching over the eggs, a mother octopus neglects to forage for food, weakening her over time. Despite declining physically, the octopus continues to show fierce dedication to her eggs3.

Since an octopus’ offspring is vulnerable, they have evolved this incredible protective behavior as a vital survival strategy. The mother’s constant attention keeps the eggs healthy and repels predators.

The female octopus eventually dies when the eggs hatch, ensuring she doesn’t threaten the baby octopuses. Today, researchers study this behavior and neurobiology to understand the strategies and physiological mechanisms behind their short lifespan and intense devotion. 

12. Octopuses have arms and legs

Octopus suckers
Photo by Sigmund on Unsplash

The word “octopus” comes from the Greek "októpus," denoting their unique anatomy. Their tentacles serve as eight arms and legs, serving distinct roles in their daily activities. 

Six of their tentacles work as arms the octopus uses to feed, sense its environment, and manipulate objects. Likewise, these arms are incredibly dexterous, with hundreds of suckers that let the animal grip various objects. Moreover, these suction cups allow the octopus to taste its surroundings, vividly depicting its environment.

The octopus’ remaining two limbs are practically its legs, which help propel them across the ocean floor and through the water while swimming. You can find these legs near the back of their body.

Sometimes, an octopus uses its two limbs to walk across the seabed while elevating the rest of its body. Further, octopuses can jet backward through the water by forcefully expelling a stream of water from a flexible, funnel-like muscular tube called a siphon.

An octopus' unique anatomy, comprising eight arms, helps the octopus move with extraordinary versatility. As a result, they can navigate various environments and adapt to different situations.

Fun fact: The term "octopus" originates from the Greek word "októpus," which translates to "eight foot," a fitting name for these marine creatures known for their eight distinct arms.  

13. Octopuses breathe through their skin

Octopuses can also breathe through their skin, known as cutaneous respiration. Breathing through their skin handles 40% of an octopus’ oxygen intake, letting them thrive in several aquatic environments. Water also helps the process, enabling oxygen to pass through the animal’s skin passively. 

A significant amount of gas is exchanged when an octopus’ skin is damp, allowing it to survive for a short time outside of water or in intertidal zones. Oxygen passes right through its moist skin and into its blood vessels. Then, oxygen courses throughout the body to fill the octopus’ metabolic needs. 

Octopuses living in regions with inconsistent water oxygen levels must breathe through their skin to survive. Likewise, they need this ability when exposed to open air during low tide. Cutaneous respiration doesn’t mean that octopuses can survive outside of water for the long term, but it gives them an advantage when moving through habitats or adapting to their changes. 

14. The Giant Pacific Octopus is the largest species in the world

The Giant Pacific octopus (Enteroctopus dofleini) is the largest known octopus species on Earth, weighing an incredible 150 lbs and having an arm span of 30 feet. You can find them in the North Pacific's coastal waters, thriving in the cold depths of Alaska, Southern California, and Japan. Under the sea, they often live in rocky areas and reefs about 2,000 feet from the ocean floor.

The reddish-brown giant Pacific octopus can rapidly change colors to blend into its surroundings through specialized pigment cells called chromatophores on their skin. While changing colors, they can avoid predators and sneak up on their prey.

Besides their ability to change colors, these octopuses are also highly intelligent and curious. They are often interested in foreign objects that wander into their habitat, so they primarily interact with divers. These animals are also a food source for larger ocean predators like sharks, sea otters, and seals.

15. The blue-ringed octopus is one of the most venomous creatures in the world

blue-ringed octopus
A blue-ringed octopus. Photo by Kris-Mikael Krister on Unsplash

While it looks small and harmless, the blue-ringed octopus carries one of the deadliest venoms in the animal kingdom. They live mainly in the Pacific and Indian Oceans, particularly around Indonesia, Japan, and Australia.

When threatened, these octopuses show glowing bright blue rings. Moreover, they might only measure five to eight inches in diameter, but they carry the extremely potent tetrodotoxin, a neurotoxin that is 1,200 times more potent than cyanide1.

The blue-ringed octopus is reclusive by nature, though they do encounter humans from time to time. When they bite, the tetrodotoxin in their venomous saliva enters the bloodstream and blocks sodium channels, disrupting nerve cell membranes.

As a result, victims suffer numbness, nausea, vomiting, difficulty breathing and swallowing, and even heart failure. There is still no known antivenom for blue-ringed octopus bites. However, victims must be taken immediately to the nearest hospital for medical support, like artificial respiration, giving them a chance to survive.

Just avoid disturbing or touching this octopus in its natural habitat to avoid being bitten. Respect the blue-ringed octopus appropriately and avoid them to keep yourself and the animals safe.

16. Octopuses are threatened by habitat loss, pollution, and overfishing

Like many of their fellow sea creatures, Octopuses face serious threats from pollution, overfishing, and habitat loss, which have triggered worldwide conservation efforts.

For example, organizations have helped create marine reserves and protected areas, safe spaces for octopuses to live and support the ecosystem's health. Similarly, these areas help balance the octopus population through sustainable fishing practices like size restrictions and catch limits. 

Moreover, organizations and governments have implemented stricter regulations on waste disposal, chemical runoff from agriculture and industry, and plastic use to mitigate sea pollution.

Besides, public education campaigns teach communities about conserving octopuses to maintain a balanced and healthy marine ecosystem. Many nations have agreed to cooperate and sign agreements, like CITES, to assist in regulating the trade of threatened octopus species.

Related: To further explore the animal kingdom, check out some of the other animals that start with O.

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1

Williams, Becky & Lovenburg, Vanessa & Huffard, Christine & Caldwell, Roy. (2011). Chemical defense in pelagic octopus paralarvae: Tetrodotoxin alone does not protect individual paralarvae of the greater blue-ringed octopus (Hapalochlaena lunulata) from common reef predators. Chemoecology. 21. 131-141. 10.1007/s00049-011-0075-5.

2

Huffard, Christine & Caldwell, Roy & Boneka, Farnis. (2010). Male-Male and Male-Female Aggression May Influence Mating Associations in Wild Octopuses (Abdopus aculeatus). Journal of comparative psychology (Washington, D.C. : 1983). 124. 38-46. 10.1037/a0017230.

3

Huffard, Christine & Caldwell, Roy & Boneka, Farnis. (2008). Mating behavior of Abdopus aculeatus (d’Orbigny 1834) (Cephalopoda: Octopodidae) in the wild. Marine Biology. 154. 353-362. 10.1007/s00227-008-0930-2.

4

Sara Maria Fossati, Francesca Carella, Gionata De Vico, Fabio Benfenati, Letizia Zullo, Octopus arm regeneration: Role of acetylcholinesterase during morphological modification, Journal of Experimental Marine Biology and Ecology, Volume 447, 2013, Pages 93-99, ISSN 0022-0981

5

Amodio, P., Boeckle, M., Schnell, A. K., Ostojíc, L., Fiorito, G., & Clayton, N. S. (2019). Grow Smart and Die Young: Why Did Cephalopods Evolve Intelligence?Trends in ecology & evolution34(1), 45–56.

6

Alleva, Enrico & Tramacere, Antonella & Manciocco, Arianna. (2011). A catalogue of body patterning in cephalopoda. Annali dell'Istituto Superiore di Sanità. 47. 475-475.

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