Trichoplax adhaerens F. E. Schulze (Placozoa): The Formation of Swarmers

Flageilated swarmers representing an alternative mode of asexual reproduction are budded off as hollow spheres at the dorsal surface. They are covered by cells of the dorsal epithelium and the interior cavity is lined by ventral epithelium. Fiber cells are in the interspace. Early primordia in the interspace between both epithelia of the mother animal are cavities filled with granular material and surrounded by non-flagellated epithelium cells. No mitoses are seen during growth of the bud whose interior becomes densely flagellated as is characteristic for the ventral epithelium. Fiber cells are passively included. The bud at first forms a bulge at the dorsal surface which is then pinched off. The flattened shape of Trichoplax is attained via cup-shaped and C-shaped intermediate stages after opening of the hollow sphere.