FIGURE 9.

Life Strategies in Placozoa: Schematic representation of feeding and reproductive stages described in this study. The density of food substrate predominantly determines formations of different morphological stages. Dense algal substrate led to the formation of aggregates from multiple animals (“social” feeding behavior). In aging culture, the formation of specialized spherical structures was observed from the upper cell layer of placozoans, and it was shown that spheres could harbor multiple bacteria. In contrast, the formation of small juvenile animals or “swarmers” might have different etiology and development from the lower cell layer, as shown in the cross-section of Trichoplax.