Nudibranchs - Decorative encyclopedic board - Ernst Haeckel, Kunstformen der Natur

Reproduction engraving of: Nudibranchs

Original title Nudibranchia - Nacktkiemen-Schnecken

Poster of Aeolis - Molluscs of the class of Snails or Gasteropods (Order of Nudibranchs, nudibranchia)

Illustration from the book Kunstformen der Natur, which is a collection of artistic lithographs of natural sciences published by the German biologist Ernst Haeckel between 1899 and 1904.

This naturalistic illustration is part of an overall style inspired by Ernst Haeckel, which greatly influenced the emerging Art Nouveau movement at the beginning of the ^20th century. This work, illustrating the impressive beauty and great diversity of the biological world, was complemented by a certain amount of scientific information, some excerpts of which are reproduced below.

This information is over 120 years old and some of it may be outdated!

Scientific classification:

 Mollusca Phylum
Class of Gastropods (Gasteropoda)
Legion of Opisthobranchs (Opisthobranchia)
Order Nudibranchs (Nudibranchia)

Scientific notice (extract) accompanying the poster print of Nudibranchia - Nudibranches :

The form-rich order of Nudibranchs belongs to the legion of opisthobranch gastropods and is distinguished from the others by the complete absence of a shell and the shell-forming mantle; however, since their juvenile stages (embryos and larvae) possess these important soft-body protective organs of gastropods, we must conclude, according to the fundamental biogenetic law, that these "naked slugs"—like all other gastropods—descended from primitive shell-bearing gastropods. The cause of the phylogenetic regression of the mantle and shell lies in the lifestyle of the nudibranchs, which usually hide among the dense branches of seaweed trees on the sea coast and crawl slowly; here, a heavy, solid calcareous shell would only hinder free movement. By adapting to the manifold forms and bright colors of these marine plants, the nudibranchs have acquired that protective resemblance to their environment that protects them from attacks by other marine animals. Many of them are distinguished by extremely bright coloration and an elegant shape of their delicate, very flexible and extensible body. At the anterior, wider end of the ovoid or leaf-shaped body, nudibranchs usually bear one or two pairs of tentacles; the anterior, smaller ones are labial tentacles of a simple shape; the posterior, larger ones are olfactory tentacles, usually retractable into sheaths and characterized by a flaky structure. The gills, which in other molluscs are hidden between the edge of the foot and the edge of the mantle, protected by the dorsal shell, have passed onto the back in nudibranchs following the regression of the mantle and shell; here they are found free and uncovered, in the form of numerous delicate filaments, leaves, feathers, shafts, etc. Sometimes the gills are arranged in two longitudinal rows (Figs. 3, 5 and 6), sometimes in numerous transverse rows (Figs. 1 and 2), sometimes they form a crown which surrounds the anus in a star shape (Figs. 4 and 7).

Species present on the Nudibranchs - Aeolis naturalist board :

• Hermaea bifida
• Aeolis coronata
• Dendronotus arborescens
• Idalia elegans
• Doto coronata
• Tritonia hombergii
• Ancula cristata