Odd dynamics of living chiral crystals

TL;DR

This study reveals that swimming starfish embryos spontaneously form long-lasting chiral crystals exhibiting self-sustained oscillations and unconventional deformation behaviors, driven by hydrodynamics and development, advancing understanding of nonequilibrium chiral active matter.

Contribution

It provides the first experimental evidence of living chiral crystals formed by multicellular organisms and links their dynamics to hydrodynamic and developmental factors.

Findings

Starfish embryos spontaneously form chiral crystals.

Living crystals exhibit self-sustained chiral oscillations.

Crystals show unconventional deformation behaviors.

Abstract

Active crystals are highly ordered structures that emerge from the self-organization of motile objects, and have been widely studied in synthetic and bacterial active matter. Whether collective crystallization phenomena can occur in groups of autonomously developing multicellular organisms is currently unknown. Here, we show that swimming starfish embryos spontaneously assemble into chiral crystals that span thousands of spinning organisms and persist for tens of hours. Combining experiments, theory, and simulations, we demonstrate that the formation, dynamics, and dissolution of these living crystals are controlled by the hydrodynamic properties and natural development of embryos. Remarkably, living chiral crystals exhibit self-sustained chiral oscillations as well as various unconventional deformation response behaviors recently predicted for odd elastic materials. Our results provide direct experimental evidence for how nonreciprocal interactions between autonomous multicellular components may facilitate novel nonequilibrium phases of chiral active matter.