Part of the show Plant Science, Composting and Mosquito Repellents
Jennifer in Boston asked:
How do Venus fly traps sense their prey without nerve cells and how do they contract without muscles?
That's a very good question, and in fact some work has been done on that quite recently. It turns out that the Venus fly trap has two disc-shaped leaves that invert themselves when an insect touches them. This happens very quickly, and they discovered this by doing time-lapse photography. The scientists who discovered it painted ultraviolet dots on the Venus fly trap so they would show up when they shone UV light on to the plant. They took 400 photographs per second while triggering a Venus fly trap and could map what happened. The analogy they used is that if you take a tennis ball, cut it in half and then turn it inside out, it will sit there quite happily. However, if you come along and just touch it very lightly, it pings back again.