A threatened species is any species which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of critical depensation, a mathematical measure of biomass related to population growth rate. This quantitative metric is one method of evaluating the degree of endangerment without direct reference to human activity.
Desmoulin's whorl snail is a species of small air-breathing land snail, a terrestrial pulmonate gastropod mollusc or micromollusc in the family Vertiginidae, the whorl snails.
Vertigo genesii, common name the round-mouthed whorl snail, is a species of small air-breathing land snail, a terrestrial pulmonate gastropod mollusc or micromollusc in the family Vertiginidae, the whorl snails.
Lithoglyphus naticoides, the gravel snail, is a species of small or minute freshwater snail with an operculum, an aquatic gastropod mollusk in the family Lithoglyphidae.
Theodoxus fluviatilis, common name the river nerite, is a species of small freshwater and brackish water snail with a gill and an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites.
Pupilla alpicola is a species of minute air-breathing land snail, a terrestrial pulmonate gastropod mollusk or micromollusk in the family Pupillidae.
Achatinella apexfulva is an extinct species of colorful, tropical, arboreal pulmonate land snail in the family Achatinellidae, once present on Oahu, Hawaii. A. apexfulva is the type species of the genus Achatinella. The specific name, apexfulva, meaning "yellow-tipped", refers to the yellow tip of the snail's shell. Inspired from the taxon, the species has been given common names such as yellow-tipped Oʻahu tree snail or Hawaiian yellow-tipped tree snail. Officially, it is listed as ‘critically endangered’ by the IUCN, however, this is because its conservation status has not been updated in 28 years.
Bythinella bicarinata is a species of very small freshwater snail, an aquatic gastropod mollusk in the family Amnicolidae.
Lamellidea novoseelandica is a species of minute air-breathing land snail, a terrestrial pulmonate gastropod mollusk or micromollusk in the family Achatinellidae. This species is widespread in New Zealand and eastern Australia.
Vallonia enniensis is a species of small land snail, a terrestrial pulmonate gastropod mollusk or micromollusk in the family Valloniidae.
Helicopsis striata is a species of air-breathing land snail, terrestrial pulmonate gastropod mollusk in the family Geomitridae.
Ruthenica filograna is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Clausiliidae, the door snails, all of which have a clausilium.
Valvata piscinalis, common name the European stream valvata or European valve snail, is a species of small freshwater snail with gills and an operculum, an aquatic gastropod mollusk in the family Valvatidae, the valve snails. It is also known as Cincinna piscinalis.
Bythinella austriaca is a species of very small freshwater snail with an operculum, an aquatic gastropod mollusk in the family Amnicolidae.
Pseudotrichia rubiginosa, sometimes known as the "German hairy snail", is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Hygromiidae, the hairy snails and their allies.
Marstoniopsis is a genus of minute freshwater snails with a gill and an operculum, aquatic gastropod mollusks or micromollusks in the family Amnicolidae.
Vertigo parcedentata is a species of small, air-breathing land snail, terrestrial pulmonate gastropod molluscs or micromollusks in the family Vertiginidae, the whorl snails.
Xerocrassa geyeri is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Geomitridae. It is also known as Trochoidea geyeri.
Zonites embolium is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Zonitidae.
