The Alvinellidae are a family of small, deep-sea polychaete

Polychaete

The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...

 worm

Worm

The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

s endemic to hydrothermal vent

Hydrothermal vent

A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both...

s in the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. Belonging to the order Terebellida

Terebellida

Terebellida make up a suborder of the Polychaeta class, commonly referred to as "bristle worms". Together with the Sabellida, the Spionida and some enigmatic families of unclear taxonomic relationship , they make up the order Canalipalpata, one of the three main clades of polychaetes...

, 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

Galápagos Islands

The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...

 by the crew of the DSV

Deep Submergence Vehicle

A Deep Sea Submergence Vehicle is a deep diving manned submarine that is self-propelled. The term DSV is generally one used by the United States Navy, though several navies operate vehicles that can be accurately described as DSVs...

 Alvin

DSV Alvin

Alvin is a manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. The vehicle was built by General Mills' Electronics Group in the same factory used to manufacture breakfast cereal-producing...

. 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

Pompeii worm

Alvinella pompejana, , is a species of deep-sea polychaete worm...

 (Alvinella pompejana), is thought to be the most heat-tolerant complex organism on Earth. Mitochondria start to break down at temperatures of 122-131°F (50-55°C), apparently providing an upper limit for eukaryote

Eukaryote

A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...

s. Under laboratory conditions, in a pressurized aquarium with a heat gradient, worms of the species Paralvinella sulfincola, chose water heated to 122°F (50°C) and made brief forays into water as hot as 131°F (55°C). Unlike other (chemosynthetic

Chemosynthesis

In biochemistry, chemosynthesis is the biological conversion of one or more carbon molecules and nutrients into organic matter using the oxidation of inorganic molecules or methane as a source of energy, rather than sunlight, as in photosynthesis...

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

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 relationship with thermophilic

Thermophile

A thermophile is an organism — a type of extremophile — that thrives at relatively high temperatures, between 45 and 122  °C . Many thermophiles are archaea...

 bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

; 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
  • Species Alvinella caudata
  • Species Alvinella pompejana - Pompeii worm
    Pompeii worm
    Alvinella pompejana, , is a species of deep-sea polychaete worm...
    
    
• 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
    Paralvinella sulfincola is a species of worm of the Alvinellidae family that thrives on undersea hot-water vents. It dwells in the hottest of waters, thriving in temperatures that would kill most other animals...
    
    
  • Species Paralvinella unidentata