Universal calcium fluctuations in Hydra morphogenesis

Oded Agam, Erez Braun*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Understanding the collective physical processes that drive robust morphological transitions in animal development necessitates the characterization of the relevant fields involved in morphogenesis. Calcium (Ca2+) is recognized as one such field. In this study, we demonstrate that the spatial fluctuations of Ca2+ during Hydra regeneration exhibit universal characteristics. To investigate this phenomenon, we employ two distinct controls, an external electric field and heptanol, a gap junction-blocking drug. Both lead to the modulation of the Ca2+ activity and a reversible halting of the regeneration process. The application of an electric field enhances Ca2+ activity in the Hydra’s tissue and increases its spatial correlations, while the administration of heptanol inhibits its activity and diminishes the spatial correlations. Remarkably, the statistical characteristics of Ca2+ spatial fluctuations, including the coefficient of variation and skewness, manifest universal shape distributions across tissue samples and conditions. We introduce a field-theoretic model, describing fluctuations in a tilted double-well potential, which successfully captures these universal properties. Moreover, our analysis reveals that the Ca2+ activity is spatially localized, and the Hydra’s tissue operates near the onset of bistability, where the local Ca2+ activity fluctuates between low and high excited states in distinct regions. These findings highlight the prominent role of the Ca2+ field in Hydra morphogenesis and provide insights into the underlying mechanisms governing robust morphological transitions.

Original languageAmerican English
Article number066002
JournalPhysical Biology
Issue number6
StatePublished - 1 Nov 2023

Bibliographical note

Publisher Copyright:
© 2023 The Author(s). Published by IOP Publishing Ltd


  • Hydra regeneration
  • bistability
  • morphogenesis
  • universal calcium fluctuations


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