Dr. Daren Watson, assistant professor of mechanical engineering at Florida Polytechnic University, stands beside the rainfall simulator used in his research to determine how water-walking insects (water striders) survive torrential downpours. The research was published in the Proceedings of the National Academy of Sciences (PNAS), one of the world’s top multidisciplinary scientific journals.
A Florida Polytechnic University professor’s groundbreaking study has revealed how tiny water-walking insects survive torrential rainstorms, potentially paving the way for advances in biomimetics and water pollution solutions.
Dr. Daren Watson, assistant professor of mechanical engineering, published his findings in the Proceedings of the National Academy of Sciences (PNAS), one of the world’s top scientific multidisciplinary journals.
The research, which began in 2021, used advanced high-speed photography techniques to focus on understanding how water striders survive strong rainfall. It found that a combination of natural buoyancy, interaction with small air pockets, and instinct help keep the insects alive.
Watson's team has begun applying its findings to research on microplastics, which are similar in size to water striders.
“We can better understand how microplastics enter water bodies during adverse environmental conditions like torrential downpour,” Watson said. “This knowledge can inform the risk that our hydrosphere faces with respect to pollution and increased weather activity.”
The research also has potential applications in biomimetic design.
“We now know how rain will interact with these very small millimetric devices,” he said, suggesting possible uses for tiny and robust aquatic devices like buoys.
Watson and his team created a rain simulator that produced water drops which mimicked the size and speed of raindrops in a lab environment. What they learned were fascinating features of the insects’ morphology that contribute to their survival, he said.
“They’re covered with densely packed micro-hairs, and this allows them to be extremely water repellent.” Watson said.
When a raindrop hits a water strider, it pushes the insect below the surface. However, he explained the micro-hairs create a protective air bubble, or plastron, which prevents it from drowning and aids with the buoyancy of the insect.
After being submerged, the insect pops back up with a resulting water jet and is pulled below the surface again, provided the insect remains attached to the collapsing jet. Water striders submerged because of this series of events can survive underwater for 10 minutes or more.
“These insects are actually born below the water, and from that moment, they have to swim to the surface and pierce it to attain that rest state on top of the surface,” Watson said. “Similarly, when they’re submerged in a storm, they're able to swim and then at an appropriate time cut the surface of the water to attain their usual position back on top of the surface.”
Watson and his team are now turning their attention to land-based insects, specifically fire ants, to further close the gap in understanding insect interactions with rainfall. As with the water strider research, a team of undergraduate research assistants is working to advance the effort.
“I’m excited to continue conducting this type of cutting-edge research here at Florida Poly,” he said. “My publication in PNAS is a testament to the strength of research that is coming and will be coming out of this institution.”
A series of high-speed photos show what happens when a drop of water strikes a water
strider. The figures are part of new research published by Dr. Daren Watson, assistant
professor of mechanical engineering at Florida Polytechnic University.
High-speed videography slowed 107 times shows the impact sequence of water striders struck by a drop of water. The video is part of a research paper published by Dr. Daren Watson, assistant professor of mechanical engineering at Florida Polytechnic University, who sought to determine how the tiny insects survive heavy rains. The research was published in the Proceedings of the National Academy of Sciences (PNAS), one of the world’s top multidisciplinary scientific journals.
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