Tevnia

Tevnia is a monotypic genus of deep‑sea vestimentiferan tube worms within the family Siboglinidae. The sole recognized species, Tevnia jerichonana, was first described in 1985 after specimens were collected from the hydrothermal vent fields on the East Pacific Rise near the Juan de Fuca Ridge. Members of this genus are notable for lacking a digestive tract; instead they obtain nutrition through a symbiotic relationship with internal chemosynthetic bacteria that oxidize hydrogen sulfide emitted by the vent fluids.

The worms form elongated, flexible tubes composed of chitinous material, which are anchored in the sediment or directly on vent structures. The body is divided into a dorsal and ventral region, with a conspicuous plume that functions in gas exchange and the acquisition of sulfide for the bacterial symbionts. Individuals can exceed one meter in length, though much of this length is contributed by the tube rather than the animal itself.

Tevnia jerichonana inhabits a range of vent habitats from the East Pacific Rise to the Mid‑Atlantic Ridge, typically colonizing areas where vent fluids are relatively low in temperature compared to those preferred by the related genus Riftia. The species’ distribution and physiological adaptations have made it a model organism for studies of chemosynthetic symbiosis, physiological responses to extreme environments, and the evolution of gut-less annelids.

Research on Tevnia contributes to broader understanding of deep‑sea ecosystems, biogeochemical cycles of sulfur and carbon, and the potential for life in analogous extraterrestrial habitats.