Body wall structure in the starfish Asterias rubens.

Abstract in brief

• The starfish Asterias rubens has a body wall made of magnesium calcite ossicles connected by collagen tissue and muscles, with its stiffness varying due to the mechanical flexibility of collagen, allowing for changes in shape.
• Researchers used techniques like trichrome staining, X-ray microtomography, and SAXD to analyze the structure and organization of the starfish's muscular and collagenous components, revealing detailed 3D architecture and collagen fibril orientation.
• The study found that muscle and collagen arrangements facilitate body shape changes through muscle contraction and relaxation, with collagen fibril alignment varying between regions, reflecting different tension states and contributing to the starfish's structural flexibility.]