Organisms whose cells have a nucleus — eukaryotes — have traditionally been separated into four ‘kingdoms’; now they have been reorganized into six. The authors of the revision hope that it will bring ...

Since the Victorian era, categorizing the natural world has challenged scientists. No group has presented a challenge as tricky as the protists, the tiny, complex life forms that are neither plants ...

Just as the human body serves as a habitat for bacteria and other microbes, diverse, tiny organisms known as protists host their own microbiomes. "We know there are many symbionts in the world, but it ...