Engineering Aquaman

The deepest fathoms of the ocean are dark, cold, and under immense pressure that, for most people, is almost unfathomable. And yet, despite these harsh conditions, complex organisms like fish and crustaceans not only survive in that environment but thrive.

Understanding how those organisms have evolved to withstand their environment could be the key that allows humans to more easily explore the depths. Researchers at the University of Pittsburgh are joining an interdisciplinary team, led by Georgia Tech, that will explore and take inspiration from the biology, chemistry and evolution of deep-sea fish to create materials that can withstand the immense pressures and conditions of the ocean and explore like never before. The five-year project, “Bio-Inspired Material Architectures for Deep Sea (BIMADS),” received a combined $7.5 million from the U.S. Department of Defense (DoD) through its Multidisciplinary University Research Initiative (MURI) program, with $2 million allocated to the Pitt contributors.

“This environment on our own planet is as odd to us as conditions on Mars or the moons of Saturn,” said Lance Davidson, William Kepler Whiteford Professor of bioengineering at Pitt, who joins this project along with Anna Balazs, the John A. Swanson Chair of Engineering and Distinguished Professor of Chemical and Petroleum Engineering. “It tests the limits of our understanding of biology, and I’m excited by the opportunity to see materials that are as adaptive as biological tissues.”  

While Davidson’s work primarily examines the biological and mechanical properties of cells and developing embryos, Balazs’s research looks at the effects of chemistry on cell mechanics, and vice versa. Together, they bring their expertise to a group with broad expertise in marine biology, biomimetic materials, chemistry, hydrogel synthesis, biohybrid material fabrication, and the design, mechanics, and dynamics of architected structures.

The project is led by Georgia Tech’s Alper Erturk, professor in the George W. Woodruff School of Mechanical Engineering, and Yuhang Hu, associate professor in the School of Chemical and Biomolecular Engineering. In addition to Davidson and Balazs, the team includes John Costello from Providence College, Shashank Priya from the University of Minnesota, and Andrew Sarles from the University of Tennessee.

“This group brings together people researching biology, doing simulations, and creating materials, and  working together, they are investigating how these creatures and their material properties are linked,” said Balazs. “Fish are, themselves, a material. If we can understand them—chemically, biologically, and mechanically—we can try to replicate it.”

Under Pressure

The pressure at sea level is about a tenth of a megapascal, while a pressure cooker brings that pressure up to about two-tenths of a megapascal. 

“At these depths, organisms are living at 40-80 megapascals of pressure where water begins to invade and destabilize biomolecules. It’s hard to communicate the magnitude of change at those pressures,” said Davidson.

One of the most exciting mysteries that Davidson hopes to unravel is how organisms can grow and develop at these depths. 

“I'm really interested in how organisms are shaped, and how they're formed, and how cells do things like generate force. Most of those motions require cells to be highly adaptive,” explained Davidson. “That adaptability requires that proteins and their complexes come apart and go back together really quickly, making them super sensitive to these high pressures. Fifteen million years of evolutionary adaptations have allowed these organisms to colonize the deepest ocean. Can we identify and make these same adaptations to surface-dwelling organisms?”

Balazs will look at the same problem from another angle.

“My lab examines how the mechanical properties of materials are affected by local changes in chemistry, light, or other stimuli in their surroundings—and how that interaction in turn affects the properties of the surroundings,” Balazs said. “The idea here is for others in the group to identify the properties of these fish, and we will try to come up with a mathematical, molecular-scale model that could account for this amazing resilience."

The pressure, however, is not the only consideration; the entire environment impacts how these creatures are able to thrive in the deepest parts of the ocean. Most creatures from shallower depths only visit these depths after death, when their bodies disintegrate and fall as “snow” that the deep-sea creatures eat. But beyond that, the creatures are also consuming bacteria from that slurry of ocean refuse—bacteria that may also influence their unique resilience.

“There’s a whole ecosystem there that we have to understand, including the fish’s microbiome, which produces some of the chemicals that allow them to live at those depths. The connection is fascinating,” said Balazs. “You can’t think of anything in isolation, and that’s why you need a cross-disciplinary team like this one to put the pieces together.”