Meeting Abstract
Hagfish make a unique material with remarkable properties. When provoked or attacked, the animal releases a small volume of biopolymer/biofilament material that unfolds, assembles,and expands in water by a factor of 10,000. The resulting gel is cohesive, forming a clogging network used for defense. The successful use of the defense gel is remarkable considering that hagfish cannot control the concentration of the resulting gel directly; they simply exude a concentrated material into an “infinite” sea of water. This raises questions about the robustness of gel formation and properties across a range of concentrations. In this work, we study the concentration dependent mechanics of hagfish defense gel. We observe that viscoelastic properties are linearly dependent on concentration over the range explored. From our observations of similar power-law creep response at all concentrations, we infer that hagfish slime has a self-similar structure regardless of its concentration. Using constitutive model fits, we propose that this self-similarity originates from a concentration-independent fractal dimension of the underlying slime structure. With simple geometric arguments, we show that the ultra-soft mechanics of slime results from the bending dominated response of the underlying fibrous microstructure. Our findings illustrate unusual properties of slime, which may be vital in the context of its physiological use, and may provide inspiration for the biomimetic design of materials.
