The Legendary Blanket Octopus

The Blanket octopus is one of those animals that legends could be made of. Imagine being at sea hundreds of years ago fishing day and night, fighting the elements, battling giant fish and encountering large sea faring animals without knowing what they are. I think of this whenever I read about "sea monsters" or giant krakens that have taken down ships and drowning the entire crew. Is it all fish tales by drunken fishermen or is it possible that some of these stories actually have roots in reality, regardless of the rum. After my first encounter with a full sized female blanket octopus, I was told such a story exists about a giant octopus type creature that lives in the Balayan bay. Oddly enough, this giant creature was told to exist in roughly the same area that we had our once in a lifetime experience. Having that encounter and considering what these early fishermen experienced is enough for me to draw a direct line to connect the dots from the present to the past and to realize, these are the creatures that legends are made of.

The Blanket Octopus is perhaps one of the most mysterious sea creatures of all times. They are a pelagic octopus that live their entire lifecycle in the open ocean which not only make’s them hard to find, but even harder to study. Much of what I know about them and the information presented here is gleaned from books, the internet, and further formed by personal observations from having multiple personal encounters with them. What i have learned is that the Blanket octopus is a complex animal with intriguing behaviors which range from the way they mate and reproduce to hunting strategies and defense. One thing is for sure, nothing can truly prepare you for the moment you encounter one of these incredible sea creatures.

Small Male Blanket Octopus

My first encounter with a fully grown female Blanket Octopus was truly an unforgettable experience that was instantly seared into my memory as if it happened a few hours ago. It was late in the evening, the water was cold and I was the last diver in the water. We had guests visiting from Belgium that wanted to experience blackwater diving but sadly on this night, the dive was rather slow. As I was finning back to the downline i saw a huge shadow pass cross our strand of lights. At first, i thought it was a massive jellyfish, then as i got a bit closer it looked like a fat ray of some kind. Preparing for the shot as I finned towards it, the details of this large mystery creature began taking shape. Suddenly, It turned towards me and quickly closed the gap between us. The first thing I noticed was it's basketball sized head and coloration's of white and pink. It had black golf ball sized eyes that were deepset and seemed to be looking straight at me as it nearly ran me over. It was then, at that exact moment that I overwhelmingly knew what I was looking at, this bizarre sea creature is a giant blanket octopus! 

Its at moments like these that I hear the words of my mentor, Joe Liburdi screaming in my head, "Chance of a lifetime, don't F*** it up" and I had every intention not too.

A fully grown female Blanket Octopus with eggs ( T. gracilis)

When your shooting with a 60mm lens in this circumstance the only thing to do is "BTFU" so I began finning backwards to put some space between me and the monster occy, but it kept coming straight towards me. I did everything i could to get a shot, any shot. No one would believe me if i only came back with a story.  As I was struggling to photograph this beast, I was continuously shining my powerful hand torch towards the surface hoping one of my guests would see the commotion and jump back in. Realizing that the octopus was as curious of me, as I was of it,  I began to relax and observe it   casually orbiting our lit downline. Finally, I saw lights from my buddy coming down from the surface   and the two of us had our first experience of a lifetime, together with this incredible beautiful creature.

A female blanket Octopus can reach 6 plus feet in size without opening its blanket. **

The encounter ended only when the flood light on my camera began to blink red which now turned this once in a lifetime encounter into a rescue mission to save the evidence. We lumbered back onto the boat stunned, giddy and crazy with adrenaline as we shared our experience with the other's on the boat who were now all kicking themselves for not joining. Later that night and only after downloading the images, i realized that our “blanky" was obviously a female as she was also carrying eggs. WOW! i yelled, Oh my god, this is *#*# insane!. It was 3:00am and im sure i woke up the entire resort!

The Blanket Octopus Contains 4 known species:

1 T. gelatus-a gelatinous deep water Tremoctopus, cosmopolitan and found in tropical and temperate waters

2 T. robsoni-Known from the waters off of New Zealand

3 T. gracilis-Palmate octopus-Found in the Indo-Pacific Region **

4 T. violaceus, violet colored- Lives in the Atlantic

The four different octopus can be found in almost all of the planets oceans but each inhabit a different region, sans the polar regions. Their lifecycle can last up to 5 years and have been observed hunting in the same area for an extended period of time. Being a pelagic animal means they don’t make a burrow in the sand or create a home like other octopuses do. These Octopus mate, hunt, feed and thrive in the open ocean and can roam from the depths of the dark zone to the surface, truly master’s of their domain.

Over the last few year,  I’ve been lucky enough to have multiple encounters with the Male’s and Females and have also been lucky enough to come away with a few decent photos. To have these kinds of encounters requires a willingness to stay out all night on the sea along with a huge scoop of luck.

                                    A Male Blanket Octopus, about the size of a garden pea, fully grown!

Unique in appearance and unique in behavior the Tremoctopus are immune to the deadly nematocysts of many cnidarians including the Man O’war jellyfish. It is reported that juvenile Tremoctpus rip the stinging tentacles from the jellyfish then holds them with their lateral arms, whipping them about to sting their prey and perhaps to protect themselves. Many photos show the trailing tentacles and clearly illustrate that this is indeed a common behavior. Oddly enough, we don’t have a population of Man O’war jellyfish in our bay which leads me to assume that they aren’t selective and will use the tentacles of any venomous jellyfish. 

A female Blanket towing cnidarians tentacles of some kind

The sexual behavior is also quite interesting. The male of the species exhibits the highest degree of sexual dimorphism yet to be discovered. The female can measure up to 2 meters in length while the males only reach a size of  2 centimeters, size and weight ratios differ as much as 10,000 times. Male Tremoctopus use a specialized arm called the hectocotylus like other male octopus which contains its sperm pack. The male only needs to touch the female with this specialized arm as it instantly sticks  then snaps off, perhaps without her even knowing. The arm then creeps down or somehow finds its way into the ovum of the female where she crushes it, releasing the sperm and fertilizing her eggs when the time is right. Hatching is intermittent.

The male, like other octopus having completed his life’s work, now dies. However the female still has a long life ahead, brooding and caring for her eggs until she finally dies from starvation much like other Octopus. Research says the eggs are kept in a “sausage shaped calcareous secretion” but i couldn'tmake that out from my photos.

Rocky, the flying squirrel !

The Tremoctopus gets is common name from the blanket that it can quickly unfurl and retract. When fully extended they resemble “Rocky, the flying squirrel” and fly through the water in much the same manner. The texture of the blanket looks like an exaggerated version of the webbing that a common octopus has and uses to web over their prey when hunting. However, these guys deploy the blanket to make themselves look bigger and perhaps to hunt and catch crustaceans or other cephalopods like the paper nautilus. The thin membrane is colorful and ocellated much like the feathers of a peacock with a pink, purple-green hue.

Other cool facts:

  • They can also detach their webbing to ensnare a would be predator or to evade as well as ink.  
  • The web is attached to the 3rd and 6th arms of the female, palmated by the 4th and 5th arm.
  • They will snap their arms outward repeatedly, tightening the blanket as it moves through the water.

Most extreme example of sexual dimorphism in nature, yet to be discovered 

Male Blankets might be small, but they are mighty and have a complicated relationship with the female. Its also reported that she might not even know when she mated as the sperm loaded arm from the male, snaps off after making contact with the female then finds its own way to the holy grail. If you think about this a little, it makes sense. The female, being so large can glide through the water making contact with multiple males while she is fertile,  increasing the odds of a higher rate of fertilized eggs. 

A female Blanket, hunting at the surface in the Balayan bay

Blanket Octopus Movie


Like a said above, there is nothing quite like encountering one of these majestic animals in the wild and i'm looking forward to learning more about these incredible creatures. The Blanket Octopus is nothing short of incredible!

All images were shot with Nikon D500 and D850|60mm lens|Sea and Sea Strobes, Housing and Ports| Kraken Sports downline and torches | ultralight clamps

Video shot with

Nikon D850|60mm + Kraken wide angle conversion lens| Kraken 12k torches

Now get out there and have an adventure!

Mike Bartick