(Image: Sponberg Lab, Georgia Tech
How do you spot a small white, swaying flower on a dark night? It鈥檚 no challenge for hawkmoths.
of Georgia Institute of Technology in Atlanta and his team have figured out the secret to the moths鈥� night vision by testing them with robotic artificial flowers (see above). By varying the speed of a fake flower鈥檚 horizontal motion and changing brightness levels, the team tested moths鈥� abilities under different conditions.
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It has been theorised that the moth brain slows down, allowing their visual system to collect light for longer, a bit like lengthening a camera鈥檚 exposure. But the strategy might also introduce blur, making it hard to detect fast movement.
If the moths were using this brain-slowing tactic, they would be expected to react to fast flower movements more slowly in darker conditions. The team found that there was indeed a lag. It helped them see motion in the dark while still allowing them to keep up with flowers swaying at normal speeds.
The size of the lags matched the expected behaviour of a slowed nervous system, providing evidence that moths could be slowing down the action of neurons in their visual system.
Previously, placing hawkmoths in a virtual obstacle course revealed that they vary their navigation strategies depending on visibility conditions.
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