The Alvinellidae are a family of small, deep-sea

polychaete Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...

worm Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always). Worms vary in size from microscopic to over in length for marine polychaete wor ...

s endemic to

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 in the

Pacific Ocean 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 ...

. Belonging to the order

Terebellida Terebellida make up an order of the Polychaeta class, commonly referred to as "bristle worms". Together with the Sabellida, the Spionida and some enigmatic families of unclear taxonomic relationship (e.g. the Saccocirridae), they make up the ...

, the family contains two genera, ''Alvinella'' and ''Paralvinella''; the former genus contains two valid species and the latter eight. Members of the family are termed alvinellids. The family was first described in 1979 after discoveries made off the

Galápagos Islands The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...

by the crew of the DSV ''

Alvin Alvin may refer to: Places Canada *Alvin, British Columbia United States *Alvin, Colorado *Alvin, Georgia *Alvin, Illinois * Alvin, Michigan *Alvin, Texas * Alvin, Wisconsin, a town *Alvin (community), Wisconsin, an unincorporated community Other ...

''. The ship subsequently lent its name to the family and genera within it. The worms build mucus tubes and extend red feathery gills. Members of the Alvinellidae are noted for their exceptional heat tolerance: one species, the

Pompeii worm ''Alvinella pompejana'', the Pompeii worm, is a species of deep-sea polychaete worm (commonly referred to as "bristle worms"). It is an extremophile found only at hydrothermal vents in the Pacific Ocean, discovered in the early 1980s off the Gal ...

(''Alvinella pompejana''), is thought to be the most heat-tolerant complex organism on Earth.

Mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...

start to break down at temperatures of , apparently providing an upper limit for

eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

s. Under laboratory conditions, in a pressurized aquarium with a heat gradient, worms of the species ''Paralvinella sulfincola'', chose water heated to and made brief forays into water as hot as .CNN.com "Study finds worms thriving in hot-water"
– 14 April 2006 Unlike other (

chemosynthetic In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic compounds (e.g., hydrogen gas, hydro ...

) vent-dwelling worms, alvinellid worms possess a digestive tract. However, they do rely on an episymbiotic relationship with

thermophilic A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...

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 ...

; hair-like growths of the bacteria living on the worm's back are thought to offer thermal protection to the worm.

Family Alvinellidae

*Genus ''

Alvinella ''Alvinella'' is a genus of annelids belonging to the family Alvinellidae. The species of this genus are found in Southeastern Asia and Northern America. Species: *'' Alvinella caudata'' *''Alvinella pompejana ''Alvinella pompejana'', the P ...

'' ** Species ''Alvinella caudata'' ** Species ''Alvinella pompejana'' –

*Genus ''Paralvinella'' ** Species ''Paralvinella bactericola'' ** Species ''Paralvinella fijiensis'' ** Species ''Paralvinella grasslei'' ** Species ''Paralvinella hessleri'' ** Species ''Paralvinella palmiformis'' ** Species ''Paralvinella pandorae'' ** Species ''

Paralvinella sulfincola ''Paralvinella sulfincola'', also known as the sulfide worm, is a species of polychaete worm of the Alvinellidae family that thrives on undersea hot-water vents. It dwells within tubes in waters surrounding hydrothermal vents, in close proximity ...

'' ** Species ''Paralvinella unidentata''

References

{{Taxonbar, from=Q3896207 Terebellida Animals living on hydrothermal vents