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17 Day Octopus Facts You’ll Never Forget

Day octopus facts will leave you spellbound!

The day octopus (Octopus cyanea), also known as the big blue octopus after the typical blue circles on its body, is a unique species of octopus belonging to the family Octopodidae. With a body that can reach a size of at least 6.3 in (16 cm) with arms of around 31.5 in (80 cm), this highly intelligent and smart species of marine cephalopods can hide in plain sight due to their remarkable ability to camouflage. Even though these invertebrates have a typically brown-colored body, they can rapidly change their appearance to assume elaborate skin textures, colors, and patterns, helping them blend in with the surroundings. Since these octopuses feed during the daylight hours, their ability to camouflage is an exceptional defense mechanism against predators. Another bewildering quality of these cephalopods is that they can shoot out a dark cloud of black ink when threatened by predators.

Commonly found in the warm and shallow tropical Indo-Pacific waters from the coast of eastern Africa to the Hawaiian islands, the day octopus dens amidst coral reefs and other marine rubble. They are related to the squid and cuttlefish and feed on fishes as well as mollusk and crustacean prey such as crabs, shrimps, and bivalves.

There is a lot more to these quirky animals! Read on to find out.

If you like what you read, do check out more fun and interesting facts about octopus and California two-spot octopus at Kidadl.

Day Octopus Interesting Facts

What type of animal is a day octopus?

The day octopus, or the big blue octopus (Octopus cyanea), is a species of marine cephalopods of the family Octopodidae.

What class of animal does a day octopus belong to?

Day octopuses belong to the class Cephalopoda, which also includes cuttlefish and squid.

How many day octopuses are there in the world?

The exact global population size of the day octopus (Octopus cyanea) is not known.

Where does a day octopus live?

Day octopuses excavate dens amidst coral reefs, in the sand, or coral rubble. The coral reef may be located at depths of 3-328 ft (1-100 m) below the surface of the water. In addition, day octopuses can also be found dwelling in seagrass beds and rocky, sandy, or muddy ocean bottoms.

What is a day octopus's habitat?

The natural geographical range and habitat of the day octopus include the tropical Indo-Pacific waters. These ocean-dwelling creatures are commonly found in warm and shallow marine environments, spanning from the Hawaiian Islands in the Pacific Ocean to the Red Sea around northeastern Africa. Some big blue octopuses have also been reported along the coasts of Seychelles, Somalia, Tanzania, Madagascar, as well as in the Mediterranean Sea.

Who does day octopus live with?

The day octopus, or the big blue octopus, is mostly a solitary creature that does not interact with its own kind except during mating. These octopuses exhibit very aggressive behavior, and some larger individuals are even known to feed on smaller ones. They are quite socially repulsive animals and will choose to dwell in solitary dens if possible.

How long does a day octopus live?

The big blue octopuses have an average lifespan of 12-15 months, both in the wild and in captivity. The longest recorded lifespan of these octopuses is 18 months in captivity as well as in the wild.

How do they reproduce?

The mating behavior of male day octopuses is typically polygynous, meaning that one male may mate with several different females. Mating is not seasonal, and these octopuses generally reproduce all year round. However, female members breed only once during their lifetime and die soon after the eggs hatch because they stop eating and lose weight. Even in the case of males of the species, the suckers on the arms enlarge after they have mated several times. Once the suckers are fully enlarged, males lose the ability to change color and soon die.

Once these octopuses reach reproductive maturity at about 10-12 months of age, they start making spermatophores. Males use their fully-grown third right arm to insert the spermatophores into the mantle cavity of the female. Mating usually takes place on solid surfaces or inside a den during the day when the octopuses are foraging. After mating, a big blue octopus female will typically lay about 700,000 eggs on average, each measuring about 0.1 in (0.2 cm) in length and weighing around o.01 oz (0.2 g). The eggs take approximately 60 days to hatch, after which the female dies. Only the female day octopus participates in parental care of the eggs, taking meticulous care of the unborn young without even stopping to eat.

What is their conservation status?

According to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, the day octopus is a species of Least Concern.

Day Octopus Fun Facts

What does day octopus look like?

The day octopus is an intelligent shape-shifter with an appearance more or similar to that of common octopuses. They can change not only their body color but also have a unique ability to alter the texture and pattern of their skin. The color changes in a way that it blends with the substrate as the octopus moves across the ocean floor.

Just like any other octopus (Octopus vulgaris), the big blue octopus has a massive head, eight long arms (modified muscular foot), and a reddish-brown skin tone. They lack the hard shell that usually characterizes other mollusks. When males reach about seven to nine months of age, they develop large suckers on the arms.  In addition, these octopuses have dark and oval false eyespots devoid of the iridescent rings that mark the base of the arms. The dark eyespots are rarely visible, depending on the displayed patterns of individual members.

Day octopuses have a ridge-like texture on their body.

How cute are they?

The big blue octopus is anything but cute. It rather looks like a huge blob of slime with hardly distinguishable features.

How do they communicate?

The ability to camouflage is not only a means of protection against predators but also a way to communicate with other octopuses. These animals are known to assume specific colors to communicate with each other. For instance, when males try to attract females, the former change into a darker color. Their eyesight is also quite well-developed, and they can spot prey from a distance of about 26 ft (8 m), waiting for the prey to come close enough so that it can be trapped. In addition, the big blue octopus can change colors rapidly like a flash of lightning to alert members of their own kind. The tactile senses of the males are used for mating.

How big is a day octopus?

The mantle length of the big blue octopus can go up to 6.3 in (16 cm), and the arm-to-arm length can be as much as 31.5 in (80 cm). Males have a longer third right arm which can reach a length of up to  19 in (48.2 cm). The big blue octopus is generally slightly smaller than the mimic octopus, which is around 23.6 in (60 cm).

How fast can a day octopus swim?

The exact swimming speed of the big blue octopus is not known. However, they are known to crawl rather than being active swimmers.

How much does a day octopus weigh?

The approximate weight of male and female big blue octopuses range between 7-232.6 oz (198.4-6594 g), with the average weight of the species being about 42.3 oz (1199.1 g).

What are their male and female names of the species?

Male and female octopuses are not known to have any distinct names.

What would you call a baby day octopus?

When they hatch, any baby octopus is called a larva.

What do they eat?

Big blue octopuses have a diverse diet, particularly when the availability of smaller prey is high. They hunt during the daytime and usually prey on small marine fish, molluscs, and crustaceans like crabs and shrimps. Juveniles have a similar diet that is predominated by small-sized prey. Interestingly, many bigger octopuses, like the Giant Pacific octopus are known to consume food in the range of 2-4 % of their own body weight!

Are they dangerous?

Big blue octopuses are not known to be aggressive or dangerous towards humans. However, these ocean creatures can exhibit aggressive behavior towards each other, with larger individuals devouring smaller ones. Females are specifically known to show cannibalistic behavior during the breeding season, a phenomenon known as sexual cannibalism. When threatened by predators, these octopuses squirt a cloud of black ink to blind the predator and inhibit the latter's sense of smell.

Would they make a good pet?

In general, octopuses do not make great pets, and they are better left in their natural ocean habitat among rocks and coral reefs. The price of pet octopus species can range between 20-1,000 USD and keeping them as pets can be quite a costly affair.

Kidadl Advisory: All pets should only be bought from a reputable source. It is recommended that as a potential pet owner you carry out your own research prior to deciding on your pet of choice. Being a pet owner is very rewarding but it also involves commitment, time and money. Ensure that your pet choice complies with the legislation in your state and/or country. You must never take animals from the wild or disturb their habitat. Please check that the pet you are considering buying is not an endangered species, or listed on the CITES list, and has not been taken from the wild for the pet trade.

Did you know...

The species name cyanea of the big blue octopus (Octopus cyanea) is a Greek term meaning sky blue, inspired by the blue rings on the octopus's skin.

During pre-mating courtship, the male day octopuses show a dark brown body color with white spots. On the other hand, females are in full camouflage and do not don the white spots.

Like other octopus species, the big blue octopus has three hearts. Surprisingly, one of these three hearts stops beating when the animals are swimming, perhaps due to some physiological reason.

The big blue octopus can change their body color naturally due to the presence of specialized skin cells called chromatophores.

The big blue octopus has salivary glands that can secrete venom. The poisonous substance ejected from the salivary glands is used by the animal to kill its prey; the octopus then uses its sharp beak to crack open the shell of the prey (such as snails and crabs). In addition, the predator octopus also has the ability to drill holes in the prey's shell with its radula (rasping organ) to inject a substance that separates the prey's flesh from its shell.

Fun fact: octopuses are thought to be quite smart as they have a memory and can learn things quite fast. Many octopuses can also find their way around mazes!

Is octopus a day hunter?

Yes, unlike other species of octopus, like the blue-ringed octopus, the big blue octopus is a daytime hunter.

Why does an octopus have 9 brains?

Octopuses have nine brains, a central one in addition to eight smaller ones to control each of the eight arms independently.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! For more relatable content, check out these coconut octopus facts and Giant Pacific octopus facts pages.

You can even occupy yourself at home by coloring in one of our free printable O is for octopus coloring pages.

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