Remarkable Blanket Octopus seen after 21 years

This article will take you through the remarkable invertebrate, the octopus and in the latter part of the article, we will talk about the rare sighting of the blanket octopus Tremoctopus violaceus in the great barrier reef.


Octopus are one of the most remarkable invertebrates. They belong to class cephalopods. They can be venomous too. Their sizes differ vastly. Some octopuses can be huge whereas some are tiny. Octopuses not only differ in their size but vastly also in their habitats. Octopus are very intelligent and complex animals as compared to other similar invertebrates and hence can survive in a lot of complex ecosystems. Octopus can be commonly seen in:-

  • Deep-Sea
  • Coral Reefs
  • Kelp forests (as in the image)
  • All Oceans
  • Along rocky shorelines.

Octopuses at a given time can appear smooth or spiky. Octopuses don’t have any hard parts with an exception of the beak. This is the reason that octopus can pass through any space as long as it’s bigger than its eyeball. This gives an evolutionary advantage to octopuses and allows them to hide in crevices in the oceans. This allows the octopus to escape from large predators and other sea-dwelling animals.

Camouflage in Octopus-octopus most remarkable invertebrate

Animal Kingdom 

Octopus belongs to the kingdom Animalia. They are part of the second-largest phylum of the animal kingdom Mollusca. 

Class- Cephalopoda

Order- Octopoda (the order consists of 300 octopus species )

The interesting thing about the octopus is that unlike its fellow Mollusca members who are known for having shells (like snails) octopuses don’t have a shell. Octopuses show other similar features to molluscs like having bilateral symmetry, organ system-level organisation, sensory tentacles in the anterior head etc. Octopuses also have blue-coloured blood due to the presence of copper ions (Cu). Eight arms of Octopuses are their distinct feature too.

Fossil records and research have proved that ancestors of octopuses did have a shell, like all molluscs. However, due to the evolutionary processes, they lost their shells. This created a massive problem since it made them vulnerable to attack by large predators of the sea. It was this vulnerability only that led to the need for great evolutionary changes that made octopuses extremely complex and intelligent animals. This is the reason that octopuses are found in almost all sea habitats.


One of the great wonders of the evolutionary process is the camouflage technique of the octopus. Octopus can be called Masters of Disguise hence making them remarkable invertebrates. Octopus can change colour as fast as we can blink our eyes. This technique allows octopuses to escape from large predators and blend with their surroundings. This allowed them to survive for millions of years. 


Let’s see how exactly this camouflage technique works:-

  • Chromatophores: Octopuses have chromatophores in their skin. Chromatophores are tissues that are sacs filled with colour pigments almost similar to a balloon filled with a coloured dye. When you stretch the balloon the colour becomes the most vibrant. Octopus does the same and hence shows different colours according to the surroundings to camouflage. These sacs have radial muscles for stretching the sacs.
  • Iridophores: The remarkable invertebrate however does not have all the colours in its chromatophores that it requires to blend in the surrounding ocean ecosystem. Hence Octopus have iridophores below the chromatophores. These iridophores are reflective structures that bounce back electromagnetic waves after absorbing them, producing different wavelengths in the visible spectrum to dispatch other characteristic colours to the octopus that helps it blend on the ocean surface.
  • Papillae: If chromatophores/iridophores were not enough for this remarkable invertebrate called an octopus. It also papillae on the outermost surface of the skin. This papilla allows the octopus to change the texture of the skin as well. It allows it to make ridges, produce spikes to appear spiky or produce a smooth skin to blend with the surrounding corals or other sea creatures

Hence we observe a very distinct camouflage technique by the octopus that allows it to survive in almost any habitat. However, camouflage is not the greatest evolutionary wonder that makes the octopus such a remarkable invertebrate. It is the intelligence of this animal. The camouflage technique only helps if the species can very quickly detect the surroundings and hence produce colour accordingly to blend in. This is the reason Octopus is being heavily researched because they are such intelligent animals. 

octopus most remarkable invertebrate

Image source-


Octopus being so remarkable are however colour blind. Their eyes do not see any colour. The question arises then how can they camouflage so quickly? A researcher once observed an octopus camouflage 177 times in 1 hour

During the evolutionary process they become so vulnerable that they had to evolve very complex nervous systems to survive in the ocean ecosystem. Octopus has 500 million neurons, the same as Dogs and even more than cats.

It has all its neurons distributed throughout its 8 long arms. The arm of an octopus can think for itself. Even when the arms were severed from the body of the octopus they could still respond to light changes because of the photoreceptor cells that are present on the skin of their arms. It is these photoreceptors cells only that allows the octopus to detect the surrounding colours and camouflage accordingly.

Octopus evolved on a completely different spectrum as compared to mammals and other vertebrates on the evolutionary tree.

Intelligence in octopuses came long before it came in mammals and vertebrates. Ideally, it is believed that intelligence is a consequence of social interactions. This theory is also called the Theory of Social Intelligence.

Animals or humans for that matter evolve intelligent complex behaviours because of their need to socialise in a group and become productive members of society. This theory fails when it comes to remarkable cephalopod invertebrate animals called an octopus. Why is that? Let’s find out

Octopuses are observed to be extremely playful

Octopuses have shown great matric results on intelligence tests. Eg octopuses are seen to remember human faces and also perform well in learning tasks. However, octopuses are solitary invertebrates and do not live in social hierarchies and societies. Why was the need to evolve such a complex intelligence structure for them if they don’t even have any need for social bonding or why are they playful if they are solitary creatures? Why need to develop intelligence?

Answers to these questions are not so straightforward. Octopuses are so far away in the evolutionary tree with respect to vertebrates. However, intelligence in octopuses is as complex as common members of the vertebrate species.

The evolutionary process created intelligent life two times. Once with the remarkable invertebrate octopus and then with the mammals. Who is to say Intelligence in Octopus is any less than us. That’s why octopuses are compared to being as close to alien life as we have observed yet. 


Although most octopus species are not endangered, a lot of cultures are known for eating octopus as a delicacy. Koreans, Japanese and some Mediterranean cultures are known for killing octopuses for food. Animal rights activists and other scientists are completely against this barbaric practise of killing a remarkably intelligent invertebrate life form.

Rare Sighting in Great Barrier Reef

Reef guide and marine biologist Jacinta Shackleton observed the remarkable blanket octopus in the Great Barrier Reef. Shackleton conducted routine research in the great barrier reef and was stunned by witnessing the blanket octopus and its vibrant colours. She just couldn’t take her eyes off it. 

blanket octopus

Image source-

This blanket octopus was last observed 21 years ago in the north of the great barrier reef. Usually, this octopus spends its life in the deep middle oceanic waters and it’s very difficult for marine biologists and divers to go there. Hence Shackleton was taken aback observing one near the barrier reef. This is the reason that blanket octopus is one of the rarest sightings in the world. The interesting fact about this remarkable cephalopod is sexual dimorphism. A very distinct case of sexual dimorphism is observed in the blanket octopus. The female is approximately 2 metres long and has this blanket-like structure that it can shed to lure the predators. However, as compared to the female, the male is very small, approximately 2.4cm.

Genus- Blanket Octopus

The blanket octopus is part of the genus called Tremoctopus. This genus is a part of the pelagic cephalopods class belonging to phylum Mollusca and the order of Octopoda.

Tremoctopus mainly includes four species:-

  • T. gelatus
  • T. gracilis
  • T. robsoni
  • T. violaceus

Tremoctopus violaceus is the common blanket octopus that was observed by Shackelton. This species shows a distinct case of sexual dimorphism as mentioned above.

So have we finally convinced you that the octopuses are the most remarkable invertebrates or maybe even the most remarkable species of the animal kingdom? Keep reading at MBD to know more about other remarkable animal species around us.

Check out this video to observe Octopuses deeply- The Insane Biology of: The Octopus – YouTube
Another interesting fact- Do Giraffes have a bluish-purple tongue? – My Biology Dictionary




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