Vulcanoctopus hydrothermalis

You might think that a volcanic vent spewing out hot chemical soup wouldn’t be a great place to find an octopus, or any kind of life for that matter. But the vulcanoctopus, or vent octopus, calls these underwater “smokers” home — along with lots of other creatures!

These vents provide nutrients for creatures like tube worms, mussels, and crustaceans. In turn, those critters can be tasty meals for volcanoctopuses!


8.5 in (22 cm long)




Deep ocean — hydrothermal vents


Small crustaceans


Southeastern Pacific Ocean




Temperature Tolerance

This octopus can handle temperatures ranging from just 33°F (1°C) all the way up to 196°F (91°C)!

SCIENTIFIC NAME: Vulcanoctopus hydrothermalis

NICKNAME: Vent Octopus, Hot Water Volcano Octopus

Named in 1998, this is the only known species of the genus Vulcanoctopus and is the only incirrate octopus associated with hydrothermal vents.


Measurements and observations are from the 1999 French research cruise HOPE99. 

This is a small, deep-sea benthic octopus with sub-mature and mature male mantle lengths ranging 22- 56 mm (1-2 in) and total weight between 24.3 to 43.9 g (1-1.5 oz, less than 1 lb!). Volcanoctopus males have a peculiar mitre-like mantle shape that is wide, but comes to a tiny point at the tip of the mantle. We will never unsee this when looking at a bishop’s ceremonial headgear!  The arms are thin and 3-4x the mantle length. Average number of suckers per normal arm ranges 45-75, but larger animals have 130-150 suckers. For males, the third right arm is hectocotylized and shorter (1-2x the mantle length) with 65-75 suckers.

It’s thought that females may be similar in size to males. During the HOPE99 research cruise, scientists observed mating behaviors and all octopuses showed similar size and appeared mature in the recorded video from the submersible. Scientists were able to tell octopus’s maturity by seeing their gonads through the octopus’s semi-translucent thin skin.



There was an opportunity to directly measure the brooding period of the deep-sea octopus Graneledone boreopacifica, in its natural habitat. At 53 months, it is by far the longest egg-brooding period ever reported for any animal species.

Does the deep-sea Vulcanoctopus have the same brooding period? Perhaps. Because of the depths and hostile environment in which they live, it’s difficult to study them. 

OctoNation members will be the first to know when more research is published!


Vulcanoctopus has been observed and collected along hydrothermal vents of the East Pacific Rise in the Pacific Ocean from depths 2600-2832 m (8,530-9,291 ft)!


Sixteen out of the seventeen octopuses collected during the HOPE99 research cruise from depth 2631 m were males. This suggests there are fewer females or there is spatial segregation by sex. More studies are needed (find the females!) to complete the biology and ecology of this deep-sea species.


Deep-sea octopuses have colonized various habitats throughout the ocean, but studying such a mobile animal in extreme environments is a challenging task. Deep-sea submersible research expeditions conducted by different nations has uncovered detailed information about the biology and ecology of animals inhabiting hydrothermal vents. To date, Vulcanoctopus is the only cephalopod identified to inhabit this environment with such hostile conditions. 

Octopuses were found in various locations around hydrothermal vents where the water temperature greatly fluctuates. They were observed at the base of the hydrothermal vent chimney and often found on cliffs of basaltic rock covered in tube worms (Riftia pachyptila) or polycheates (Alvinellidae), and rarely associated with mussel beds.  Water temperature ranged from 1-2°C (33-35°F) at the base of vent chimney to 1.6-10°C (35-50°F) around tube worm plumes and 7-91°C (44-196°F) close to polycheates. 

Volcanoctopus were also observed around hydrothermal vent zones where crabs (galatheids) and zoarcid fish were found.


While slowly crawling across the bottom, Volcanoctopus uses its dorsal (front) arms to explore and its ventral (back) arms for propulsion. It has been confirmed that this species eats amphipods (tiny shrimp-like animals) and crabs (probably galatheids). Like other incirrate octopuses, it is possible that this species also preys upon polycheates and bivalves. More observations are needed to fully understand Volcanoctopus’s diet.


The use of remotely operated vehicles (ROVs) or manned submersibles can influence animal behavior by changing environmental conditions as a result of spotlights, sounds, and turbulence and the physical appearance of an UFO (unidentified floating object)! However, photos, video recordings, and direct observations via manned submersibles and ROVs are still the best methods to study deep-sea animal behavior. 

Volcanoctopus has a semi-translucent white body that lacks chromatophores. Its skin is smooth with no dorsal mantle papillae or eye papillae. This species lacks an ink sac due to adaptations selected for in the deep-sea. During submersible expeditions, Volcanoctopus showed open eyelids that did not have behavioral changes or responses to submersible lights. It seems that mechanoreceptors (touch and pressure) and chemoreceptors (smell) are the main sense organs used by this octopus. 

French manned submersible “Nautile” during the  HOPE 99 research cruise filmed several Volacanooctopus that demonstrated primary (hide) and secondary (escape) defense behaviors and mating behaviors. Volcanoctopus was observed to hide in the tube worm plumes or in the cracks between rocks and “freeze” by maintaining its position in its hiding place. Its escape maneuver response, involved pushing away from the bottom or “take off” where the octopus used a sequence of 3-4 strong pulsations generated by the arm crown while the animal pulled its body into a hydrodynamic fusiform shape to maximize thrust. How much thrust? The elapsed time between each pulse was 3-4 seconds and the 4 pulses pushed the animal 3 m (9 ft) from its original location! After the pulsations, the octopus floated with its arms spread out and drifted back down. This “take off” behavior is similar to that observed in Grimpotheuthis sp. and Cirroteuthis spp. 

Scientists observed mating behavior of 5 octopuses: 4 males attempting to mate with a female. Three males were using the “mounting” mating behavior while the other male was “mating at a distance” with his hectocotlyized arm extended. Eggs were observed and were reported to be relatively small, about 10% of female’s mantle length.

Via: National Oceanography Centre

Gonzalez, A. F., Guerra, A., Rocha, F., Briand, P. (2002) Morphological variation in males of Vulcanoctopus hydrothermalis (Mollusca, Cephalopoda). Bulletin of Marine Science 7:289-298.

Rocha, F.; Gonzalez, A. F.; Segonzac, M.; Guerra, A. (2002) Behavioural observations of the cephalopod Vulcanoctopus hydrothermalis. Cah. Biol. Mar.: 299-302.

Voight, J.R. 2005. Hydrothermal vent octopuses of Vulcanoctopus hydrothermalis, feed on bathypelagic amphipods of

Halice hesmonectes. Journal of the Marine Biological Association of the United Kingdom, 85: 985-988.

Jereb, P.; Roper, C.F.E.; Norman, M.D.; Julian K Finn (eds). Cephalopods of the world. An annotated and illustrated catalogue of cephalopod species known to date. Volume 3. Octopods and Vampire Squids. FAO Species Catalogue for Fishery Purposes. No. 4, Vol. 3. Rome, FAO. 2014. 370 p

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