Ernst Haeckel (1834 – 1919)
Haeckel was a German biologist, philosopher, and artist, defender of Darwin’s ideas. He is famous for the detailed drawings that he made of countless species, and by coining terms like stem cells, anthropogeny, and ecology. He is also well known for having been the first to attempt to classify all the species in a tree of life. But what made him most famous is his theory of recapitulation: ontogeny recapitulates phylogeny. With this, he claimed that the biological development of an organism, or the embryo (ontogeny) summarizes all the intermediate forms of its ancestors throughout the evolution of the species (phylogeny). Nowadays, this theory is considered outdated.
Haeckel was an excellent illustrator. He published a compilation of color and black/white plates, titled Art Forms in Nature, consisting of 100 beautiful prints of many different organisms, many of them first discovered and described by himself. Some of the most outstanding ones are the anemones and other jellyfish, bats, octopuses, spiders, plankton, trilobites, and many more microscopic marine creatures.