Haeckel was an accomplished scientist whose ultimate fidelity was not always to empiricism. His observations of nature led to the discovery of almost 4,000 species of radiolarian, and his iconic visual forms, such as the evolutionary tree, helped to make complex information accessible and graphically intuitive, both to other scientists and to the public. But, for better and worse, romanticism also guided his brush.

The image at right depicts jellyfish called discomedusa, which Haeckel first described systematically in 1866 and later included in his popular book Art Forms in Nature. Haeckel named the species in the center of the painting Desmonema Annasethe, after his first wife, Anna Sethe, who had died years earlier. The streaming tendrils, he said, reminded him of her flowing blond hair. The painting nicely exemplifies his elegiac passion and ornate style, which would profoundly influence Europe's Art Nouveau movement and later artists.