Riftia

Riftia is a genus of large tubeworms that inhabit deep-sea hydrothermal vents. Its members lack a mouth and gut as adults and obtain nutrition from symbiotic bacteria housed in a specialized organ.

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Chemosynthesis: The production of organic compounds using energy from chemical reactions rather than sunlight. Riftia’s symbiotic bacteria use chemical energy to fix carbon and supply nutrients.
Siboglinidae: A family of marine annelids that includes bearded worms and tubeworms, many of which host bacterial symbionts. Riftia is classified within this family of unusual annelids.
Symbiosis: A close, sustained association between organisms of different species. Riftia’s dependence on internal bacteria is a striking case of symbiosis.
Galápagos Rift: A mid-ocean ridge spreading center in the eastern Pacific Ocean. Riftia was first discovered at hydrothermal vents in this region.
Thioautotrophic bacteria: Bacteria that obtain energy by oxidizing reduced sulfur compounds and use it to fix carbon dioxide. These symbionts provide most of the organic nutrients Riftia needs.
Annelid: A segmented invertebrate animal in the phylum Annelida, which includes earthworms and leeches. Despite its striking vent adaptations, Riftia is an annelid.
Endosymbiosis: A symbiotic relationship in which one organism lives inside another. Riftia houses its bacterial partners within specialized internal tissue.
East Pacific Rise: A fast-spreading mid-ocean ridge in the eastern Pacific Ocean. Dense Riftia aggregations occur at hydrothermal vent fields along this ridge.
Trophosome: A specialized internal organ in vestimentiferan tubeworms that houses dense populations of symbiotic bacteria. Riftia’s trophosome is the tissue where its nutritional symbiosis is concentrated.
Tube worm: An aquatic worm that lives in a tube it secretes or constructs. Riftia lives inside a protective tube anchored to the vent seafloor.