Baleen whales are incredible at filter feeding; they became the largest animals on the planet by eating huge amounts of tiny food.
Now, a local scientist is trying to find out if the same system that helps whales catch plankton might also be able to catch something that’s a similar size — tiny fragments of plastic.
“They have evolved the perfect instrument to catch and eat planktonic animals, and that makes them perfect to collect microplastics,” said Jean Potvin, a professor of physics at St. Louis University.
Plastic has become ubiquitous in the environment. Larger pieces break down into microplastics and nanoplastics that researchers have found in water, soil and even human bodies. There is a global race to solve this problem. Potvin is one of a handful of St. Louis-area scientists studying nature-based solutions they think could be key to removing plastics from the environment.
What whales know
In a basement lab at St. Louis University, Potvin and his students have constructed a machine to test a whale-inspired filtration system. A tube of water connects on both ends to what looks like a large fish tank. Inside, Potvin has made an imitation whale mouth.
The bristly filter structure that grows from certain whales’ jaws is called baleen. It’s made out of keratin, like hair or nails. Although baleen whales’ smile is full of pearly white, they don’t have teeth.
“Instead of teeth, you have to imagine rows of plates that are arranged like a comb,” Potvin said. “And these plates, this baleen system acts as a filter.”
Potvin brings a hose over to fill the tank, then turns on a drill press attached to a propeller that creates a current in the water. He grabs a fishnet filled with tiny beads of plastic and dumps them in. They swirl through the pipe and head toward the imitation baleen. Just as Potvin expected, the beads lodge in the filter.
“You can see all those particles being caught,” Potvin said. “And then I'll simulate the tongue in a moment.”
It’s early days for Potvin’s experiment, and he has more to learn. He doesn’t know why the slats of baleen are placed where they are in a whale’s jaw and how that might affect the water flow through the system.
“Obviously, they have to do with generating what we call the cross flow, that is, the water that comes through and across the filtration surface, but how is it done?” Potvin wondered. “What's the optimal parameter? We don't know.”
One thing Potvin does know — this system is pretty efficient. Whales don’t use much energy to filter feed, and Potvin said that same efficiency might benefit the environment.
After Potvin and his team collect more data and do more tests, he hopes a baleen-inspired water filtration system could eventually be added to a municipal water treatment plant, to keep microplastics out of local streams and rivers.
“Microplastics are everywhere,” Potvin said. “It would be nice if we could remove it.”
Brewing an alternative
At Washington University, a new center similarly focuses on nature-inspired solutions that might reduce plastic.
The center is making biodegradable substances that could replace plastic by engineering microbial systems, said Marcus Foston, director of the center and an associate professor at Wash U.
On top of their ability to show up where they shouldn’t be, plastics are made from oil and gas, leading to climate-warming greenhouse gas emissions.
“These problems aren't simple, they're global scale,” Foston said. “And they require a bunch of different expertise.”
To explain the science behind the center’s work, Foston makes a comparison to beer.
“The microorganisms that we're using to produce beer are essentially the same kinds of microorganisms and microbes that we're using to produce plastics,” Foston said.
In beer brewing, sugars from grains feed yeast to produce ethanol. Foston said DNA is like the software for this microbial factory. By changing the DNA, it could be possible to create plastic alternatives instead of ethanol.
One of the first areas the team is targeting is fiber or textiles for clothes.
“Our goal is really to provide society with an alternative that eliminates the pollution in our land and the sea,” Foston said.
The Synthetic Biology Manufacturing of Advanced Materials Research Center launched this year with a five-year, $3.6 million grant from the National Science Foundation. Researchers from Northwestern University, Iowa State University and the University of South Florida also are involved.
