The Daring

A division of the Center
for the Study of Diagonality
in World Culture

Daring Diagonal Virtual Museum
In Certain
Natural Sponges
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We think of marine sponges as soft and pliable, but some sponges actually have glassy skeletons. The skeletons are diagonally-reinforced square lattices. This diagonal reinforcement of the skeletal structure, according to researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) “has a higher strength-to-weight ratio than the traditional lattice designs that have [been] used for centuries in the construction of buildings and bridges. …We found that the sponge's diagonal reinforcement strategy achieves the highest buckling resistance for a given amount of material, which means that we can build stronger and more resilient structures by intelligently rearranging existing material within the structure,” said Matheus Fernandes, a graduate student at SEAS.

“In many fields, such as aerospace engineering, the strength-to-weight ratio of a structure is critically important,” said James Weaver, a Senior Scientist at SEAS. “This biologically-inspired geometry could provide a roadmap for designing lighter, stronger structures for a wide range of applications.” Leah Burrows writes about this discovery in News and Events, published by SEAS. She writes: "If you’ve ever walked through a covered bridge or put together a metal storage shelf, you’ve seen diagonal lattice architectures. This type of design uses many small, closely spaced diagonal beams to evenly distribute applied loads. This geometry was patented in the early 1800s by the architect and civil engineer, Ithiel Town, who wanted a method to make sturdy bridges out of lightweight and cheap materials.”

Matheus Fernandes wrote “Town developed a simple, cost-effective way to stabilize square lattice structures, which is used to this very day. It gets the job done, but it’s not optimal, leading to wasted or redundant material and a cap on how tall we can build. One of the main questions driving this research was, can we make these structures more efficient from a material allocation perspective, ultimately using less material to achieve the same strength?”

Luckily, the glass sponges, the group to which Euplectella aspergillum — otherwise known as Venus' Flower Basket belongs — had a nearly half billion-year head start on the research and development side of things. To support its tubular body, Euplectella aspergillum employs two sets of parallel diagonal skeletal struts, which intersect over and are fused to an underlying square grid, to form a robust checkerboard-like pattern.

The discovery of symmetric geometric patterns in living organisms is not new. Ernst Haeckel’s marvelous book Art Forms in Nature analyzes the geometric structure of tiny creatures called Radiolaria. The variety of geometric patterns created by nature and beautifully illustrated in his 1862 book is breathtaking. What is startling about the geometry of marine sponges, however, is that the orthogonality of their skeletal structures is something that one might expect to find in plants or animals on the surface of the earth where gravity translates structurally into perpendicularity. But in the amorphous sea, orthogonality is a puzzling occurrence. And if that right-angle geometry is not enough on its own, the overlaid 45-degree rotation of the orthogonal grid to enhance the structural performance is mind-boggling. How did evolution ever create this rotation. One must never underestimate the creative powers of Chance and Necessity.


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