A research collaboration across three continents that aimed to gain a deeper understanding of the deep-sea sponge’s interactions with the water around it, has revealed key findings that could guide the future design of buildings, bridges, marine vehicles and aircraft.
Researchers led by Giacomo Falcucci (from the Tor Vergata University of Rome and Harvard University), in collaboration with Sauro Succi (Italian Institute of Technology) and Maurizio Porfiri (Tandon School of Engineering, New York University) created a first-ever simulation of the deep-sea sponge to find out how it responds to and influences the flow of nearby water.
A study of the remarkable structural properties of the Venus flower basket sponge (E. aspergillum) reveals how the organism's latticework of holes and ridges influences the hydrodynamics of seawater in its vicinity – this could lead to advanced designs for anything that must respond safely to forces imposed by the flow of air or water such as skyscrapers, airplanes and ships among others.
The work, ‘Extreme flow simulations reveal skeletal adaptations of deep-sea sponges’, published in the journal Nature, revealed a profound connection between the sponge's structure and function.
"This organism has been studied a lot from a mechanical point of view because of its amazing ability to deform substantially in spite of its brittle, glassine structure," said Falcucci, the first author of the study. "We were able to investigate aspects of hydrodynamics to understand how the geometry of the sponge offers a functional response to fluid, to produce something special with respect to interaction with water."
Porfiri, a co-author of the study, commented, "By exploring the fluid flow within and outside the body cavity of the sponge, we uncovered the footprints of an expected adaptation to the environment. Not only does the sponge's structure contribute to a reduced drag, but also it facilitates the creation of low-velocity swirls within the body cavity that are used for feeding and reproduction."
The structure of the sponge, E. aspergillum resembles a delicate glass vase in the form of a thin-walled, cylindrical tube with a large central atrium, siliceous spicules – this form explains their commonly used appellation, ‘glass sponges’. The spicules are composed of three perpendicular rays, giving them six points. The microscopic spicules ‘weave’ together to form a very fine mesh, which gives the sponge's body a unique rigidity and allows it to survive at great depths in the water column.
Results from the study allowed the team to explore how the organisation of holes and ridges in the sponge improved its ability to reduce the forces applied by moving seawater and how its structure affected the dynamics of flow within the sponge body cavity to optimise selective filter feeding and gamete encounter for sexual reproduction.
Co-author Succi described the study as an exemplary application of discrete fluid dynamics in general and the Lattice Boltzmann method, in particular. "The accuracy of the method, combined with access to one of the top supercomputers in the world made it possible for us to perform levels of computation never attempted before, which shed light on the role of fluid flows in the adaption of living organisms in the abyss."
According to Falcucci, the study findings have a lot of implications for the design of high-rise buildings or any mechanical structure, from skyscrapers to low-drag novel structures for ships, or fuselages of airplanes.