Abstract
The bell-shaped members of Cnidaria typically move around by swimming, whereas the Hydra polyp can perform locomotion on solid substrates in aquatic environment. To address the biomechanics of locomotion on rigid substrates, we studied the ‘somersaulting’ locomotion in Hydra. We applied atomic force microscopy to measure the local mechanical properties of Hydra’s body column and identified the existence of differential Young’s modulus between the shoulder region versus rest of the body column at 3:1 ratio. We show that somersault primarily depends on differential tissue stiffness of the body column and is explained by computational models that accurately recapitulate the mechanics involved in this process. We demonstrate that perturbation of the observed stiffness variation in the body column by modulating the extracellular matrix (ECM) polymerization impairs the ‘somersault’ movement. These results provide mechanistic basis for the evolutionary significance of differential extracellular matrix properties and tissue stiffness.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
The manuscript has been re-written for better lucidity. All the figures have been revised. A new figure and a section in the results for the same has been added (Figure 7) containing scanning electron microscopy images of Hydra mesoglea at the shoulder and body region to bolster our claim of differential tissue stiffness in hydra and how it is a function of fibrillar collagen. From our collaboration, 3 new authors from Weizmann Instituite of Science have been added to the author list who helped us with the SEM.
