ABSTRACT
The animal phylum Placozoa, with its most prominent model species, Trichoplax adhaerens, has attracted substantial attention for biological and medical research across disciplines. The extremely simple placozoan bauplan shows a remarkably low number of different somatic cell types and represents a unique system for developmental research. Major gene families involved in the complexity of cell differentiation and tissue architecture in higher animals have their gene regulatory counterparts in placozoans. Nine somatic cell types have so far been described in placozoans, and more than 80% of the cells are epithelial. As a major boon as an experimental animal, Trichoplax possesses a remarkably effective ability to regenerate body parts (or even a whole individual from a small portion of tissue).
