Extension is usually accomplished by expansion of hydrostatic cavities around which most embryonic tissues are organized. Animal tissues are in a state of balanced mechanical stress arising from tension due to contractile cytoskeletons and extension due to stretching around a hydrostatic chamber. Hydra consist of two epithelia stretched around a hydrostatic gastric cavity. I am examining the arrangement of cells in order to understand which forces each cell might contribute to morphogenesis. The epithelial cells have basal processes containing microfilaments and these probably contribute the main cellular forces for shaping the hydra.
Many biological forms are complex.
Fractal geometry offers a framework for viewing certain complicated shapes as single entities. The shapes of fern leaves are a natural model system because they have many characters of fractals. Some computational algorithms for generating fractals produce leaf patterns. These algorithms provide succinct ways of describing these shapes, and also suggest ontogenic pathways. Another focus of my research is the general biology, taxonomy and evolution of hydra.