Haeckel was born in Postdam Prussia. As a young man, he studied medicine and was granted a doctorate in medicine in 1857. Although Haeckel began his career as a physician, that soon changed. When he read Charles Darwin's book On the Origin of Species, he abandoned medicine and pursued an education and career in the field of zoology. In 1862, Haeckel became a professor of comparative anatomy and focused his work on various invertebrates such as sponges, annelids, and radiolarians. During the mid-1800s, naming species was a significant part of the practice of zoology and during a trip to the Mediterranean, Heackel set about assigning names to almost 150 previously undescribed species.
Sadly, Haeckel's reputation and legacy are not free from tarnish. He once stated that "politics is applied biology", a slogan that was later adopted by Nazi propagandists and who also used his views as justification for spreading racism and promoting social Darwinism. Additionally, his science has been questioned due to lack of empirical support and possible data fabrication.
Despite Charles Darwin's On the Origin of Species having been a strong influence on Heackel, he was not entirely convinced that natural selection was the driving force that shaped evolutionary change. Heackel was an evolutionist, but was not quite a Darwinian evolutionist.
Heackel was a prolific writer and natural history illustrator. His books included titles such as The History of Creation, Systematic Phylogeny, The Riddle of the Universe, Last Words on Evolution, and The Last Link. His natural history illustration culminated in the publication of Kunstformen der Natur (Artforms of Nature) in 1904. The book included 100 lithographic and autotype prints of a variety of organisms including arachnids, turtles, bryozoa, sea anemones, and many others.
Ernst Heackel died on August 9, 1919.