Why did Ermst Haeckel divide protoctists into a different kingdom?

Answer 1

Ernst Haeckel divided protoctists into a separate kingdom to address the diversity and complexity of unicellular organisms that did not fit neatly into the established kingdoms of plants and animals. He recognized that these organisms, which include algae, protozoa, and some fungi, exhibited unique characteristics distinct from multicellular life forms. By creating the kingdom Protoctista, Haeckel aimed to provide a more accurate classification system that reflected the evolutionary relationships among these diverse life forms. This classification helped to advance the understanding of biological diversity and the evolutionary tree of life.