Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: Anaerobic prokaryotes do not need oxygen. They use fermentation or other methods of respiration that don't require oxygen. In fact, some cannot tolerate oxygen. An example is a bacterium that infects wounds and kills tissues, causing a condition called gangrene. Answer: anaerobic
What do you call prokaryotes that do not need oxygen for respiration?