Complex sentence: The Shasta crayfish ("Pacifastacus fortis"), also known as the placid crayfish, is an endangered crayfish species endemic to Shasta County, California, where it is found only in isolated spots on the Pit River and Fall River Mills.
Split into simpler sentences: The Shasta crayfish ("Pacifastacus fortis"), also known as the placid crayfish, is an endangered crayfish species endemic to California. It is found only in isolated spots on the Pit River and Fall River Mills.