The Venus Fly Trap is not the only carnivorous plant with a snap-trap. Aldrovanda vesiculosa, the waterwheel plant, has one too but it’s not always been clear how it works. Simon Poppinga and colleagues have taken a closer look, and published their findings in Scientific Reports. “Our study is the first to show in detail how the carnivorous waterwheel plant (A. vesiculosa) captures its daphniid prey,” they write.

A. vesiculosa is plant that lives in the water, eating small prey as it passes. The A. vesiculosa trap looks similar to the Venus Fly Trap trap, with two lobes that snap shut around the prey. The challenge for studying  A. vesiculosa is the speed.  A. vesiculosa is fast, with the traps operating in as short a time as tenth thousands of a second, about the same time as the blink of an eye.

To tackle the traps, Poppinga’s team used high-speed photography, similar to the setup they had already used for examining the slightly faster bladderwort plants. Keeping a focus on the traps, the scientists could review how the prey triggered the trap and, if it was lucky, how it escaped.