Aylacostoma
Encyclopedia
Aylacostoma is a genus
of tropical freshwater snail
s with an operculum
, aquatic
gastropod molluscs in the family
Thiaridae
.
These snails are considered to be extinct in the wild.
, Argentina
, feeding on the algae that grow attached to the rocks on the bottom. The water in the area is saturated with oxygen
, from the fast-moving waters.
Aylacostoma is a parthenogenic species: the population consists of only females, which increase in number by asexual reproduction
. The females give birth to a small number of larva
e, no more than three, that are born very well developed, so they have the physical strength needed to attach to a rock and resist the strong current.
, almost all the suitable habitat for Aylacostoma was flooded. All the species are now extinct in the wild. Although a small population is kept alive in aquariums, their future is uncertain, due to the difficulties in representing in captivity the original conditions of their habitat.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of tropical freshwater snail
Freshwater snail
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....
s with an operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
, aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
gastropod molluscs in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Thiaridae
Thiaridae
Thiaridae, common name thiarids, is a family of tropical freshwater snails with an operculum, aquatic gastropod mollusks in the superfamily Cerithioidea....
.
These snails are considered to be extinct in the wild.
Species
Species within genus Aylacostoma include:- Aylacostoma chloroticumAylacostoma chloroticumAylacostoma chloroticum is a species of freshwater snail, aquatic gastropod mollusc in the family Thiaridae. This species is extinct in the wild and it was found in Argentina and Paraguay. The cause of its extinction in the wild is the building of the Yacyretá Dam on the Paraná River...
Hylton-Scot, 1953 - Aylacostoma guaraniticumAylacostoma guaraniticumAylacostoma guaraniticum is a species of freshwater snail, an aquatic gastropod mollusc in the family Thiaridae. This species is extinct in the wild and it was found in Argentina and Paraguay....
Hylton-Scot, 1953 - Aylacostoma stigmaticumAylacostoma stigmaticumAylacostoma stigmaticum is a species of freshwater snail, aquatic gastropod mollusc in the family Thiaridae. This species is extinct in the wild and it was found in Argentina and Paraguay....
Hylton-Scot, 1953
Distribution
The genus is endemic to the Yacyretá region of north CorrientesCorrientes
Corrientes is the capital city of the province of Corrientes, Argentina, located on the eastern shore of the Paraná River, about from Buenos Aires and from Posadas, on National Route 12...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
Life habits
These snails used to live in areas of white water in the Yacyretá Rapids, Paraná RiverParaná River
The Paraná River is a river in south Central South America, running through Brazil, Paraguay and Argentina for some . It is second in length only to the Amazon River among South American rivers. The name Paraná is an abbreviation of the phrase "para rehe onáva", which comes from the Tupi language...
, feeding on the algae that grow attached to the rocks on the bottom. The water in the area is saturated with oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, from the fast-moving waters.
Aylacostoma is a parthenogenic species: the population consists of only females, which increase in number by asexual reproduction
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
. The females give birth to a small number of larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, no more than three, that are born very well developed, so they have the physical strength needed to attach to a rock and resist the strong current.
Conservation status
With the building in 1993 of the Yacyretá DamYacyretá Dam
The Yacyretá Dam or Hydroelectric Power Station Jasyretâ-Apipé is a dam and hydroelectric power plant built over the waterfalls of Jasyretâ-Apipé in the Paraná River, between the Argentine Province of Corrientes and the Paraguayan City of Ayolas. The dam is named for Yacyretâ Island just upstream,...
, almost all the suitable habitat for Aylacostoma was flooded. All the species are now extinct in the wild. Although a small population is kept alive in aquariums, their future is uncertain, due to the difficulties in representing in captivity the original conditions of their habitat.