Mesozoa

The classification of living beings in systematics is a continuous subject of research. There are different systematic classifications. The taxon treated here has become obsolete through new researches or is not part of the system of the group presented in the German-language Wikipedia.

As Mesozoa (Grischs, Mitteltierchen) were formerly called multicellular animals, which, however, do not share the most important characteristics of the other animal multicellular (Metazoa) in the Zellaufbau. They have been grouped together into a group, although they are not a natural group, a so-called monophyletic taxon. Today, however, it is known that this animal group is secondary-simplified bilateral tissue.

All known mesozoa are worm-shaped and not larger than 2 mm. They consist of a generative core zone surrounded by a single-layer somatic envelope. Other characteristics are a change of sexually and asexually proliferating generations (metagenesis) and an exclusively endosymbiontic or endoparastitic life in marine vertebrates.

The two formerly grouped animal groups are: Orthonectida: Endoparasiten (ca. 30 Arten) Edit source text

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