''Vulcanoctopus hydrothermalis'' is a small

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

hydrothermal vent A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspot ...

s. It is the only known species of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

''Vulcanoctopus''.

Habitat

''Vulcanoctopus hydrothermalis'' lives along the

East Pacific Rise The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located along ...

, the border of the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

, Cocos, and

Nazca Plate The Nazca Plate or Nasca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru–Chile Trench, of the Na ...

s. It is often found near colonies of

giant tube worm ''Riftia pachyptila'', commonly known as the giant tube worm and less commonly known as the Giant beardworm, is a marine invertebrate in the phylum Annelida (formerly grouped in phylum Pogonophora and Vestimentifera) related to tube worms ...

Description

The morphology of ''V. hydrothermalis'' shows some unusual traits for an octopus, due to adaptations selected for in the deep sea, such as the lack of an

ink sac An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods, all Coleoidea (squid, octopus and cuttlefish) which dwell ...

. Its

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...

are longer than the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

arms. These feature biserial suckers. Overall, it has a mean total length of .

Behavior

The ratio of recovered individuals is skewed towards males, indicating fewer females or spatial segregation by sex. Its primary defense reaction is to freeze in place, then if needed, the secondary defense involves pushing away from the bottom then drifting back down. ''V. hydrothermalis'' uses its front arms (I dorsal and II dorsolateral) for feeling its way around and detecting and catching prey, while the back arms (III ventrolateral and IV ventral) support its weight and move the octopus forward. This species has not been observed to use

jet propulsion Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operating o ...

Prey

Its confirmed prey consist of the

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

'' Halice hesmonectes'' and crabs, which are thought to be one of their primary food sources.

References

External links

''Vulcanoctopus hydrothermalis''
at

Encyclopedia of Life The ''Encyclopedia of Life'' (''EOL'') is a free, online encyclopedia intended to document all of the 1.9 million living species known to science. It is compiled from existing trusted databases curated by experts and with the assistance of non ...

(pictures) {{Taxonbar, from1=Q1948648, from2=Q21229929 Enteroctopodidae Cephalopods of South America Cephalopods of Oceania Molluscs of the Pacific Ocean Molluscs described in 1998