Getting food can be a challenge for varying breeds of animals, but hawkmoths have a particular challenge. They feed at dusk by inserting their long proboscis into a flower in order to drink nectar.
Simon Sponberg, an assistant professor in the physics department at Georgia Tech, who reported on the moth’s visual capabilities last week in Science, said hawkmoths must maintain a hovering position, “while they’re feeding from a flower with a proboscis that can be as long as their body while the flower is moving in the wind.”
Hawkmoths must see the flower clearly. They are doing this at “light levels at which we’d have trouble seeing the hand in front of our face,” Dr. Sponberg said.
He alongside Thomas L. Daniel, with whom he studied the moths at the University of Washington before moving to Georgia Tech, and colleagues reported that one way the moths seem to cope with the darkness is to slow visual processing in their brains.
As if they were using a slower shutter speed in a camera, they are able to allow their brains to gather more light, the New York Times reported.
Dr. Sponberg’s interest is in understanding how animals “move through their world with grace and agility” and why engineering something similar for robots is so difficult. By pairing how the brain works with the physics of animals, this can aid in the engineering process.
There was previous evidence to suggest visual processing could slow down in hawkmoths, however no test of whether this was occurring while feeding in low light had taken place.
Dr. Sponberg and his colleagues designed robotic flowers and used high-speed video to record the moth’s feeding habits. If visual processing were to slow down in low light, then faster motion should be harder to detect for the moth, the same way fast action is blurred in a photograph at a slower shutter speed.
The flowers were programmed to move in several ways at once, like a hand shaking as it waves in larger motion. Using computers to break down the separate movements of the robotic flowers and how well the moth stayed in sync, the researches could see whether its tracking performance deteriorated in low light for fast motion.
It did, which supported the idea that visual processing was slowed down in hawkmoths. The biggest loss was the ability to stay in sync with the flower’s movements when those oscillations were faster than 1.7 times a second. At oscillations slower than 1.7 times a second, the moth’s ability to stay in sync with the flower did not significantly deteriorate, which meant the longer visual processing did not disrupt the moth’s ability to see and respond to those motions, the NY Times reported.