''Halicephalobus mephisto'' is a species of
nematode
The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
, among a number of other roundworms, discovered by geoscientists Gaetan Borgonie and
Tullis Onstott in 2011. It was detected in ore recovered from deep rock fracture water in several
gold mine Gold Mine may refer to:
*Gold Mine (board game)
*Gold Mine (Long Beach), an arena
*"Gold Mine", a song by Joyner Lucas from the 2020 album '' ADHD''
See also
* ''Gold'' (1974 film), based on the novel ''Gold Mine'' by Wilbur Smith
*Gold mining
...
s in
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
, , and under the surface of the Earth.
[ Onstott said that "it scared the life out of me when I first saw them moving", and explained that "they look like black little swirly things".] The finding is significant because no other multicellular organism
A multicellular organism is an organism that consists of more than one cell, in contrast to unicellular organism.
All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- ...
had ever been detected farther than below the Earth's surface.
''Halicephalobus mephisto'' is resistant to a temperature as high as 37 °C (higher than most terrestrial nematodes can tolerate),[ it ]reproduces asexually
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the fu ...
, and feeds on subterranean bacteria. According to radiocarbon dating
Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
The method was dev ...
, these worms live in groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
that is 3,000–12,000 years old.[ The worms are also able to survive in waters with extremely low levels of oxygen, lower than one percent of the level of most oceans.] It is named after Mephistopheles
Mephistopheles (, ), also known as Mephisto, is a demon featured in German folklore. He originally appeared in literature as the demon in the Faust legend, and he has since appeared in other works as a stock character (see: Mephistopheles in t ...
, the Lord of the Underworld in the Faust
Faust is the protagonist of a classic German legend based on the historical Johann Georg Faust ( 1480–1540).
The erudite Faust is highly successful yet dissatisfied with his life, which leads him to make a pact with the Devil at a crossroads ...
story, and alludes to the fact it is found so deep under the Earth's surface.
It is the deepest-living animal ever found, able to withstand heat and crushing pressure, and the first multicellular organism found at deep subsurface levels. A previously known species found at similar depths in the same study was '' Plectus aquatilis''. Borgonie said that the worm was similar to the detritus feeding species found on the surface, and probably descended from surface species. Such species are also able to survive extremes of temperature, and so, for Borgonie, the fact the first animal discovered at this depth was a worm was unsurprising.[ An updated and expanded article is found at .] The team hypothesised that the species was descended from animals on the surface that were washed down the earth's crust by rainwater.
''Halicephalobus mephisto'' worms measure from 0.5 to 0.56 mm in length. Though species in 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 ...
'' Halicephalobus'' have few distinguishing features, ''H. mephisto'' can be differentiated from other species within its genus by its comparatively long tail, which is between 110 and 130 micrometres
The micrometre (American and British English spelling differences#-re, -er, international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American and British English spelling differences# ...
in length. It is somewhat closely related to the mammalian pathogen ''Halicephalobus gingivalis
''Halicephalobus gingivalis'' is a free-living saprophagous nematode species identified and named in 1954 by Stefanski. It is a facultative parasite of horses, invading the nasal cavity, and sometimes numerous other areas, where it produces g ...
'', but is more closely related to certain unnamed species of the genus.
In 2019, genome sequencing
Whole genome sequencing (WGS), also known as full genome sequencing, complete genome sequencing, or entire genome sequencing, is the process of determining the entirety, or nearly the entirety, of the DNA sequence of an organism's genome at a ...
of the nematode indicated that there were expansions of the 70 kilodalton heat shock protein
The 70 kilodalton heat shock proteins (Hsp70s or DnaK) are a family of conserved ubiquitously expressed heat shock proteins. Proteins with similar structure exist in virtually all living organisms. Intracellularly localized Hsp70s are an importa ...
(Hsp70) and ''avrRpt2'' -induced gene 1 (AIG1) proteins, both of which are transcriptionally induced under heat stress. De novo Illumina assembly with PacBio reads produced a 61.4 Mb assembly made of 880 scaffold and 313 kb N50.
The water, in which ''Halicephalobus mephisto'' was found, contained aerobic
Aerobic means "requiring air," in which "air" usually means oxygen.
Aerobic may also refer to
* Aerobic exercise, prolonged exercise of moderate intensity
* Aerobics, a form of aerobic exercise
* Aerobic respiration, the aerobic process of cellu ...
and anaerobic
Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to:
* Anaerobic adhesive, a bonding a ...
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
. Unlike other nematodes it does not prefer ''Escherichia coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'' and will rather feed on the sulphophile endolith
An endolith or endolithic is an organism (archaeon, bacterium, fungus, lichen, algae or amoeba) that is able to acquire the necessary resources for growth in the inner part of a rock, mineral, coral, animal shells, or in the pores between minera ...
and depth specialist ''Desulforudis audaxviator
"''Candidatus'' Desulforudis audaxviator" is a monospecific genus of bacteria that lives in groundwater at depths from below the Earth's surface.
Etymology
The name comes from a quotation from Jules Verne's novel ''Journey to the Center of th ...
''. The found specimen of ''H. mephisto'' propagated through parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...
.[
]
References
{{Taxonbar, from=Q482469
Rhabditida
Nematodes described in 2011