Geometrical Models for the Growth of Unicellular Algae

We analyse various shapes obtained from a geometrical model describing the cell wall deformation of unicellular algae. Typical shapes existing in the algal world can be reproduced, especially the rhizoid, growing by tip growth only, a tip growth-lobe branching shape like the desmid Micrasterias radiata and a tip growth-lobe broadening-branching shape like another desmid Micrasterias rotata. Transitions between these different shapes are studied and related to the variations of simple parameters of the model.