A lobster shell is pretty tough. But the transparent material on the underside of the tail is perhaps even more surprising: laboratory tests show that the thin and extensible substance is as strong as the rubber used to make the tires.
Like the shell that surrounds the body of a lobster, the soft material on the underside of the crustacean's tail contains chitin, a fibrous material found in the exoskeletons of many insects and crustaceans. The team's tests revealed that the substance contained about 90% water, which gives the material elasticity. It also has a plywood-like arrangement of microscopic layers, each with chitin fibers extending predominantly in one direction, but those of neighboring layers extending in slightly different orientations. This same type of arrangement helps to give the plywood a constant resistance in several directions that a single layer of wood does not have, noted the researchers.
The membrane layer is slightly floppy and stretches almost twice as much as its normal length before starting to stiffen, reports the team in a future issue of Acta Biomaterialia. They find that the stretching of the material makes it even more rigid. Overall, the material is as strong as those used to make garden hoses, tires and conveyor belts. Another advantage of the layered arrangement of the membrane: cuts or cuts that penetrate only a few outer layers do not generally propagate in the intact layers, which makes the material "fault-tolerant".
The researchers suggest that similar materials could be used to make flexible joints, such as elbows and knees, armor or too hard suits.