Sea Urchin Spine Structure Makes It Strong And Fragile
October 3, 2012

Structure Of Sea Urchin Spine Explains Its Strength And Fragility

Lee Rannals for - Your Universe Online

Sea urchins are those round little spiky creatures in the ocean, and a study published in the journal PLOS ONE has unveiled what it is that gives those viscous looking spines their unique characteristics.

For years, scientists have been interested in the chemical composition of the sea urchin spine, but there has been no investigation of how they respond to mechanical stress.

The purple-spined sea urchin is found in tidal waters along the coast of New South Wales. The creature uses its spines for movement, sensing its environment and for protecting itself against predators or rough terrain.

The long hollow spines are made up of a single crystal of calcite arranged in a porous, intricate structure.

In the latest study, scientists have gained insight into how this unique and intricate structure enables the creature's spines to better absorb impacts and stress under some conditions, while simply snapping off in other situations.

Researchers say the finding could offer clues for creating new bio-inspired materials and more efficient engineering designs.

The sea urchin's spine strength is interesting to scientists because of the brittleness of the basic materials that it is made of, explained the study´s lead author Dr. Naomi Tsafnat from the School of Mechanical and Manufacturing Engineering at the University of New South Wales.

“While we´re not certain that this evolutionary feature is optimized, it certainly works — the longevity of this creature, having survived hundreds of millions of years, is a testament to that,” she said in a press release.

“The spine is both strong and lightweight, and has mechanical characteristics that suit the sea urchin´s needs.”

Tsafnat says the sea creature can withstand several different types of physical loads, such as compression, which allows it to maneuver and walk around but snaps easily when it needs to protect itself from predators.

The researchers used a process known as microtomography in order to create a high-resolution 3D microscopic image of a segment of spine.

They used this 3D image to create a computer model of the spine segment and then simulated various mechanical load scenarios with it.

They observed that different types of stress concentrate at different points within the architecture of the urchin´s spines. This feature contributes to the spines´ overall strength and unusual elasticity under certain types of physical stress.