Fun Blue-lined Octopus Facts For Kids

Monisha Kochhar
Aug 29, 2023 By Monisha Kochhar
Originally Published on Oct 29, 2021
Blue-lined octopus facts are interesting.

One of the most venomous marine species, the blue-lined octopus (H. fasciata), can be extremely fatal to humans. They are a sub-species of the blue-ringed octopuses, belonging to the class Cephalopoda, order Octopoda, family Octopodidae, and genus Hapalochlaena. Its scientific name is Hapalochlaena fasciata.

Inhabiting the intertidal rocky shore and shallow waters of the Pacific ocean, this species is commonly found along the shores of Southern New South Wales until Southern Queensland, in Australia. These carnivorous animals feed on crabs and small fish.

They have a slithery, moist body and a mantle of length 1.8 in (4.5 cm) approximately. They weigh around 1 oz (28.3 g).

They usually prey on crabs and small fish. These dangerous animals are yellow-brown in color with blue lines when relaxed but, when threatened by predators, blue rings appear all over the body as a sign of warning.

The mantle cavity contains the salivary glands that produce a deadly venom that causes severe health issues such as weakening of muscles, breathing problems, and even death. The female octopuses lay 50-100 eggs on average and they can live up to two years.

Keep reading to know more interesting facts about this species! Check out blue-ringed octopus facts and coconut octopus facts to learn more.

Blue-Lined Octopus Interesting Facts

What type of animal is a blue-lined octopus?

The Hapalochlaena fasciata is a type of octopus that is extremely harmful to humans. They are one of the four sub-species of the blue-ringed octopuses (Hapalochlaena lunulata).

What class of animal does a blue-lined octopus belong to?

This octopus belongs to the Animalia kingdom of class Cephalopoda.

How many blue-lined octopuses are there in the world?

These octopuses are found in abundance as they multiply by the hour. Hence, there is no concrete number to tell how many exist in the wild.

Where does a blue-lined octopus live?

The Hapalochlaena fasciata species lives in the Pacific Ocean waters, commonly found along the shores from Southern New South Wales till Southern Queensland in Australia.

What is a blue-lined octopus' habitat?

These octopuses inhabit the intertidal rocky seashores and coastal waters at depths of 49.2 ft (15 m).

Who does the blue-lined octopus live with?

These octopuses are solitary creatures that are only found in pairs during the mating season.

How long does a blue-lined octopus live?

The average lifespan of these octopuses is two years. Baby octopuses take four months to mature after hatching, and the rest of the three months are spent behind the development of the embryo.

How do they reproduce?

The reproductive behaviors of these octopuses are indeed interesting. These octopuses reach sexual maturity when they are a year old. One of the arms of the males gets transformed into a mating tool called hectocotylus.

The male octopuses slide their arms inside the oviduct (reproductive organ) of the females. After a month, 50-100 eggs are laid by the females.

The eggs hatch after a span of two months during which the eggs remain hidden under the arms of the females. The process of reproduction ends with the death of the females. The baby octopuses take four months to mature.

What is their conservation status?

 These octopuses are found in abundance and are hence, not required to be conserved. The International Union For Conservation Of Nature, or IUCN, has marked the conservation status of these octopuses as of Least Concern as they multiply by the hour, leaving a huge population behind.

Blue-Lined Octopus Fun Facts

What does the blue-lined octopus look like?

We've been unable to source an image of a blue-lined octopus and have used an image of a blue-ringed octopus and it's habitat instead. If you are able to provide us with a royalty-free image of a blue-lined octopus, we would be happy to credit you. Please contact us at

The Hapalochlaena fasciata species has a slithery, moist body with eight arms and a mantle. These dangerous animals are yellow-brown in color with blue lines when relaxed but, when threatened by predators, iridescent blue rings appear all over the body which is a sign of warning.

How cute are they?

Considering their small size and round mantle with slithery legs, these octopuses in general look really cute. The blue rings that appear all over their body enhance their appearance, making them look extremely attractive.

How do they communicate?

Octopuses produce no sound in communication. However, this species is known to communicate by using the eight long legs that they possess. Color alteration and different postures recorded on video cameras have helped researchers to gain insights into their styles of communication amongst themselves.

How big is a blue-lined octopus?

These octopuses grow around 1.8 in (4.5 cm) with eight slithery, long legs. They are smaller than a mimic octopus.

How fast can a blue-lined octopus swim?

These octopuses can swim at a speed of 24.9 mph (40 kph), which is faster than the speed of a colossal squid.

How much does a blue-lined octopus weigh?

The H. fasciata weighs around 1 oz (28.3 g). The vampire squid is bulkier than them.

What are the male and female names of the species?

The female octopuses are known as hens. There are no names assigned for the males.

What would you call a baby blue-lined octopus?

Baby octopuses are called larvae.

What do they eat?

These octopuses are carnivorous in nature and thus, eat crabs and small fish.

Are they dangerous?

If not provoked, these octopuses will show no sign of aggression. They are extremely shy and prefer living in exile.

However, if they sense danger or are touched, they have the capacity to cause death. They produce a venom known as tetrodotoxin in their saliva. They either bite or use a small apparatus to inject this neurotoxin that can cause paralysis within minutes.

Would they make a good pet?

Octopuses are extremely venomous and can cause severe health issues in humans. They are extremely shy and prefer living in solitude. Hence, these creatures must be left alone in the sea and the idea of petting them must be discarded at once.

Did you know...

The venom is not used to kill prey but is only used by these octopuses to paralyze the predators that pose a danger. They use their arms to hunt crabs and small fish and puncture their body with the help of their sharp beak.

They are extremely good at camouflaging with their environment.

Is the blue-lined octopus deadly?

All varieties of octopuses are harmful to humans and this particular species (H. fasciata) is not an exception. A deadly venom known as tetrodotoxin is produced in their saliva that can cause paralysis within minutes.

They inject this neurotoxin through a small apparatus or may bite which the victim will not be able to sense because of an extremely small beak. The victims of the sting may experience symptoms like their muscles becoming weak, breathing problems that may even result in death.

Blue-lined octopus vs. Blue-ringed octopus

The blue-lined octopus (Hapalochlaena fasciata) is a sub-species of the blue-ringed octopus. One major difference between these two creatures is that the blue-ringed octopus is pale-yellow in color while the other is brown-yellow in color with blue lines all over. However, the blue rings appear in case of both when they are faced with danger.

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 octopus facts and coconut octopus facts.

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

Second image by Totti.

We Want Your Photos!
We Want Your Photos!

We Want Your Photos!

Do you have a photo you are happy to share that would improve this article?
Email your photos

More for You

See All

Written by Monisha Kochhar

Bachelor of Arts Hons specializing in Modern Languages (French and Spanish)

Monisha Kochhar picture

Monisha KochharBachelor of Arts Hons specializing in Modern Languages (French and Spanish)

A Modern Languages graduate from the University College London, Monisha with a passion for travel and exploring different cultures. She is fluent in French and Spanish and is currently learning Hindi. Monisha enjoys discovering new foods and is an avid sports fan, following soccer and Formula 1. In her spare time, she enjoys playing tennis and watching TV shows.

Read full bio >