List of critically endangered invertebrates
As of July 2016, the International Union for Conservation of Nature (IUCN) lists 987 critically endangered invertebrate species, including 206 which are tagged as "possibly extinct". 5.5% of all evaluated invertebrate species are listed as critically endangered. The IUCN also lists 14 invertebrate subspecies as critically endangered. No subpopulations of invertebrates have been evaluated by the IUCN. Additionally 5278 invertebrate species (29% of those evaluated) are listed as "data deficient", meaning there is insufficient information for a full assessment of conservation status. As these species typically have small distributions and/or populations, they are intrinsically likely  to be threatened, according to the IUCN. While the category of "data deficient" indicates that no assessment of extinction risk has been made for the taxa, the IUCN notes that it may be appropriate to give them "the same degree of attention as threatened taxa, at least until their status can be assessed." This is a complete list of critically endangered invertebrate species and subspecies as evaluated by the IUCN. Species considered possibly extinct by the IUCN are marked as such. Molluscs. There are 581 mollusc species and 11 mollusc subspecies assessed as critically endangered. Gastropods. There are 511 gastropod  species and six gastropod subspecies assessed as critically endangered. Stylommatophora. Stylommatophora includes the majority of land snails and slugs. There are 233 species and five subspecies in the order Stylommatophora assessed as critically endangered. Endodontids. Species Subspecies Littorinimorpha. There are 181 species in the order Littorinimorpha assessed as critically endangered. Architaenioglossa. There are 48 species in the order Architaenioglossa assessed as critically endangered. Hygrophila. Species Subspecies Bivalvia. There are 69 species and five subspecies in the class Bivalvia assessed as critically endangered. Unionida. There are 66 species and five subspecies in the order Unionoida assessed as critically endangered. Margaritiferids. Species  Subspecies Unionids. Species Subspecies Arthropods. There are 394 arthropod species and three arthropod subspecies assessed as critically endangered. Arachnids. There are 47 arachnid species assessed as critically endangered. Malacostracans. Malacostraca includes crabs, lobsters, crayfish, shrimp, krill, woodlice, and many others. There are 125 malacostracan species and one malacostracan subspecies assessed as critically endangered. Decapods. There are 106 decapod species and one decapod subspecies assessed as critically endangered. Cambarids. Species Subspecies Insects. There are 195 insect species and two insect subspecies assessed as critically endangered. Orthoptera. There are 72 species in the order Orthoptera assessed as critically endangered. Odonata. Species Subspecies