IUCN Threat Categories

Categories of threat according to IUCN.

The International Union for the Conservation of Nature and Natural Resources (IUCN) recommends the classification in the following categories:

• EX – Extinct: The last remaining member of the species has died, or is presumed beyond reasonable doubt to have died.
• EW – Extinct in the Wild: Captive individuals survive, but there is no free-living, natural population. Example: Several species of Pacific tree snails (Partula).
• CR – Critically Endangered: Faces an extremely high risk of extinction in the immediate future. Example: Desmoulins' whorl snail (Vertigo moulinsiana).
• EN – Endangered: Faces a very high risk of extinction in the near future. Example: Chrysalis snail (Lauria cylindrica).
• VU – Vulnerable: Faces a high risk of extinction in the medium-term. Example: Moss bladder snail (Aplexa hypnorum).
• NT – Near Threatened: May be considered threatened in the near future. Example: Ribbed grass snail (Vallonia costata).
• LC – Least Concern: No immediate threat to the survival of the species.
• DD – Data Deficient
• NE – Not Evaluated

Critically endangered: Desmoulins' whorl snail (Vertigo moulin- siana). Picture: Gilles St. Martin (Original).

Endangered: Chrysalis snail (Lauria cylindracea). Picture: Kristiina Ovaska. Source: CalPhotos.

Vulnerable: Moss bladder snail (Aplexa hypnorum). Picture: © Alexander Mrkvicka, Vienna (mrkvicka.at).