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Rarest crayfish

Rarest crayfish
Who
Shasta crayfish Pacifastacus fortis
Where
United States
When
16 November 2013
The rarest species of crayfish is the Shasta crayfish Pacifastacus fortis. Native to Shasta County in California, USA, it is found only within isolated portions of the Pit River drainage, with an extent of occurrence of just 13 square km. Its highly fragmented population is believed to be decreasing, and it probably numbers no more than 300 specimens in total. It is categorized as "Critically Endangered" by the IUCN.