  In animals, epithelial tissues are barriers against the external environment,
providing protection against biological, chemical, and physical damage.
Depending on the animal's physiology and behavior, these tissues encounter
different types of mechanical forces and need to provide a suitable adaptive
response to ensure success. Therefore, understanding tissue mechanics in
different contexts is an important research area. Here, we review recent tissue
mechanics discoveries in a few early-divergent non-bilaterian animals --
Trichoplax adhaerens, Hydra vulgaris, and Aurelia aurita. We highlight each
animal's simple body plan and biology, and unique, rapid tissue remodeling
phenomena that play a crucial role in its physiology. We also discuss the
emergent large-scale mechanics that arise from small-scale phenomena. Finally,
we emphasize the enormous potential of these non-bilaterian animals to be model
systems for further investigation in tissue mechanics.
