From evolutionist Charles Darwin onward, scientists have pondered how the Venus' flytrap can snap its leaves closed around an insect in less than a tenth of a second even though it has neither muscles nor nervous system.
Now, using a high-speed camera, a team of researchers has shown that the rapid movement is caused by structural tension similar to that which causes a contact lens to suddenly flip from concave to convex when it is handled.
The key to the action is the complex curvature of the leaves, which creates powerful tension, according to biologist and mechanical engineer Lakshminarayanan Mahadevan of Harvard University.
Mahadevan and his colleagues painted tiny fluorescent dots on the leaves of a flytrap and then filmed it under ultraviolet light. Using mirrors to record different angles, they were able to determine how the leaves' shape changed when an insect was captured.