Witnessing how flamingos feed is truly a captivating experience. They tilt their heads in the water and perform a charming waddling dance, sifting through small crustaceans, insects, microscopic algae, and other minute aquatic morsels in shallow waters.
Victor Ortega Zimenez, a biologist from the University of California, Berkeley, recalls being captivated by this behavior in 2019 during a family visit to the Atlanta Zoo. Since then, he has pondered what transpires beneath the water’s surface.
“While the birds were stunning to observe, my main question was, ‘What hydrodynamic principles guide the filter feeding behavior in flamingos?'” he shared.
Upon returning home, he was struck by the lack of scientific literature on the subject, prompting him to embark on his own research journey. After years of careful investigation, he and his team made remarkable discoveries, detailed in a recent publication by the National Academy of Sciences. They revealed that flamingos actively use the physics of water flow to sweep up prey and direct it into their mouths.
“We’re disputing the common notion that flamingos are merely passive filter feeders,” Dr. Ortega Zimenez stated. “Just as spiders create webs, flamingos generate vortices.”
Dr. Ortega Zimenez collaborated with three extraordinarily supportive flamingos from the Nashville Zoo: Matty, Marty, and Cayenne. Zookeepers trained these birds to feed in transparent containers, allowing researchers to capture their feeding behaviors using high-speed cameras and fluid dynamics techniques. The team introduced oxygen bubbles and food particles to visualize the water flow facilitated by the birds. After observing live flamingos, they constructed a 3D model of a flamingo’s head to further investigate its biomechanics.
The researchers found that flamingos frequently and quickly retracted their heads while feeding. Each movement generated tornado-like vortices, drawing particles from the bottom to the water’s surface. Additional experiments with mechanical beaks revealed that flamingos rapidly pound their beaks while partially submerged, directing the flow of water straight to their mouths and aiding in prey capture. Their uniquely shaped L-shaped beaks played a crucial role in creating vortices and recirculating water. They utilized the surface layer for feeding, reaping the benefits of their specialized feeding techniques.
Another “surprising discovery” involved the flamingos’ feet, as Dr. Ortega Zimenez noted. Researchers explored this through mechanical models of flamingo feet and computational simulations. The dance-like movements underwater contributed to the vortices, propelling additional particles toward the waiting mouths of the birds, which feed upside down in the water. Collectively, these findings indicate that flamingos are “superfeeding machines,” employing their entire bodies in the feeding process.
Biophysicist Sunghwan Jung from Cornell University commended the study for showcasing how biological morphology and motion interact functionally with surrounding fluids.
Alejandro Rico Gevala, an evolutionary biologist at Washington University in Seattle, who was not involved in the research, also concurred, stating that the new findings challenge the idea of flamingos as merely passive filter feeders. “Numerous hypotheses have attempted to explain how their peculiar bills function,” he remarked.
In addition to elucidating that mystery, the study reveals “a distinctly evolved method for capturing elusive small prey,” he added. This research hints at another possible evolutionary purpose for the birds’ webbed feet, beyond simply functioning as paddles.
Dr. Ortega Zimenez, fueled by curiosity about the dynamics of water flow used by flamingos, is now planning to investigate what occurs within the bird’s beak during feeding. Ultimately, such discoveries may lead to bioinspired technologies aimed at addressing issues like toxic algae and microplastics, he said.
“What is the essence of filter feeding in flamingos?” he questioned. “As scientists, we aspire to understand both the shape and function of these fascinating and enigmatic birds.”
Source: www.nytimes.com
