What is Ernest Haeckel's three-kingdom system?

Answer 1

Answer

In the mid 17th century all living organisms were classified into two kingdoms, plants and animals (both multicellular organisms). However, advances in microscopy and biochemistry led to the discovery of microscopic organisms which were unicellular, so didn't fit into either group. This led Haekel to suggest the three-kingdom system in the 1860s. He added the kingdom Protista which comprised the unicellular or unicellular-colonial organisms (including the bacteria). The idea of a third kingdom lay dormant for almost a century (Whittaker, 1959). Opposition to three kingdoms heralded the start of a tradition which is still evident, involving the 'lumpers' who favour a two-kingdom scheme and the 'splitters' who support three or more kingdoms (Margulis, 1981). However by the 1960s the unchallenged position of the two kingdoms had ended and a three-kingdom systems were widely used and appeared in many Biology texts.

Answer 2

Ernst Haeckel's three-kingdom system was a biological classification system that divided all living organisms into three broad categories: Animalia (animals), Plantae (plants), and Protista (protists). This system was proposed in the late 19th century and served as an early attempt to classify and organize the diversity of living organisms based on observed morphology and characteristics.