''Alviniconcha'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of deep water

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

s, marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Paskentanidae. These snails are part of the fauna of the

hydrothermal vent Hydrothermal vents are fissures 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 hot ...

s in the Indian and Western Pacific Ocean. These and another genus and species within the same family (''

Ifremeria nautilei ''Ifremeria nautilei'' is a species of large, deepwater hydrothermal vent sea snail, a marine gastropod mollusk in the family Provannidae, and the only species in the genus ''Ifremeria''. This species lives in the South Pacific Ocean Other spec ...

'') are the only known currently existing animals whose nutrition is derived from an endosymbiotic relationship with a member of bacteria from phylum

Campylobacterota Campylobacterota are a phylum of Gram-negative bacteria. Taxonomy Until the 2021 revision of bacterial taxonomy by the ICSP, the entire phylum was classified within the Proteobacteria (synonym Pseudomonadota) as the Epsilonproteobacteria and ...

(formerly Epsilonproteobacteria) and Gammaproteobacteria, occurring as

endosymbionts An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root ...

within the vacuoles of ''Alviniconcha'' ctenidia (or molluscan gills). All species of ''Alviniconcha'' are thought to be foundational species found near hydrothermal venting fluid supplying their bacterial endosymbionts with vent derived compounds such as

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

. These snails can withstand large variations in temperature (), pH, and chemical compositions.

Description

The size of the shell varies between up to in height. The surface of the shell is studded with hairs on the

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods an ...

, which ranges from a yellow/green to brown coloring. However, this thin periostracum is often missing or degraded due to high temperatures and chemical reductants found in nearby venting fluid. While ''Alviniconcha'' has been considered cryptic for many years, morphoanatomy studies on ''A. boucheti'', ''A. kojimai'', and ''A. strummeri'' have found distinguishing characteristics of the shell and head-foot regions. These three species are the only ones known to cohabitate vent fields, all other species are found in isolated basins in the NW Pacific and Indian Oceans. Morphoanatomy has not been studied for ''A. adamants'', ''A. hessleri'', or ''A. marisindica'', thus shell variation or morphology does not yet correspond to individual species.

Life history

Knowledge gaps remain in the life history of ''Alviniconcha'', however adult shell anatomy resembles

planktotrophic Marine larval ecology is the study of the factors influencing dispersing larvae, which many marine invertebrates and fishes have. Marine animals with a larva typically release many larvae into the water column, where the larvae develop before meta ...

development. Unlike the sister genus ''Ifremeria'' whose development includes a novel "Waren's" larval form, held within a brood pouch (absent in ''Alviniconcha'').

Species

Until 2014, ''Alviniconcha'' consisted solely of the species ''Alviniconcha hessleri'', described in 1988. In 2014, increased recognition of genetic differences between populations resulted in the formal description of five

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

within the former ''A. hessleri'' that were believed to be morphologically indistinguishable from each other but that have consistent differences in

mitochondrial DNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...

sequences. New research also suggests distributions of ''Alviniconcha'' in the SW Pacific are linked to geochemical gradients and endosymbiont chemical requirements. Species within the genus ''Alviniconcha'' include: * ''Alviniconcha adamantis'' - found in the relatively shallow seamounts (less than ) of the Mariana's Arc and hypothesized to be the ancestor of all other extant ''Alviniconcha'' species. Hosts gammaproteobacterial endosymbionts. S.B. Johnson, Warén, Tunnicliffe, Van Dover, Wheat, Schultz & Vrijenhoek, 2014 * ''Alviniconcha boucheti'' - found in hydrothermal vents in the Manus, Fiji, and Lau basins ranging from in depth. Hosts epsilon-proteobacterial endosymbionts. Named after deep sea gastropod scientist Philippe Bouchet. S.B. Johnson, Warén, Tunnicliffe, Van Dover, Wheat, Schultz & Vrijenhoek, 2014 * ''Alviniconcha hessleri'' - first ''Alviniconcha'' species to be described. Found at hydrothermal vents in the Mariana Trough at depths greater than . Hosts gamma-proteobacterial endosymbionts. Most closely related to ''A. kojimai''. Okutani & Ohta, 1988 * ''Alviniconcha kojimai'' - found at hydrothermal vents of the Manus, Fiji, and Lau Basins ranging from in depth. Hosts both epsilon- and gamma-proteobacterial endosymbionts. S.B. Johnson, Warén, Tunnicliffe, Van Dover, Wheat, Schultz & Vrijenhoek, 2014 * ''Alviniconcha marisindica'' - only ''Alviniconcha'' species found in the Indian Ocean, named by T. Okutani for the latin name for Indian Sea. Found specifically at vent sites on the Central Indian Ridge ranging from in depth. Hosts epsilon-proteobacterial endosymbionts. Okutani, 2014 * ''Alviniconcha strummeri'' - named after punk musician

Joe Strummer John Graham Mellor (21 August 1952 – 22 December 2002), known professionally as Joe Strummer, was a British musician. He was the co-founder, lyricist, rhythm guitarist, and lead vocalist of punk rock band the Clash, formed in 1976. The Clash' ...

The Clash The Clash were an English Rock music, rock band formed in London in 1976. Billed as "The Only Band That Matters", they are considered one of the most influential acts in the original wave of British punk rock, with their music fusing elements ...

.A Snail So Hardcore It's Named After A Punk Rocker
at

National Public Radio National Public Radio (NPR) is an American public broadcasting organization headquartered in Washington, D.C., with its NPR West headquarters in Culver City, California. It serves as a national Radio syndication, syndicator to a network of more ...

; published December 20, 2014; retrieved March 18, 2015 Only found in the Southern Lau Basin, specifically at the Tui Mall vents sites at a depth of . Hosts both gamma- and epsilon- proteobacterial endosymbionts. S.B. Johnson, Warén, Tunnicliffe, Van Dover, Wheat, Schultz & Vrijenhoek, 2014

References

* Healy, J.M. 1992, ''Dimorphic spermatozoa of the hydrothermal vent prosobranch Alviniconcha hessleri: systematic importance and comparison with other caenogastropods''; Bull. Mus. Natl. His. Nat. Paris 4 sér A 14: 273-291 * Desbruyères, D., M. Segonzac & M. Bright (eds.). 2006. ''Handbook of Deep-sea Hydrothermal Vent Fauna.'' Second Edition Denisia 18:1-544. (Copepods 316-355)(Polychaeta 183-296)

External links

* {{Taxonbar, from=Q4738280 Paskentanidae Taxa described in 1988