Biologists Find Evidence for Electrical Signaling and Coordinated Behavior in Choanoflagellates

Scientists at the University of Bergen have uncovered a remarkable diversity of behaviors within the rosette-shaped colonies of Salpingoeca rosetta, a rare species of choanoflagellate — the closest relatives of animals.

“We found communication among the cells of the colonies, which regulates shape and ciliary beating across the rosette,” said Dr. Jeffrey Colgren, a researcher with the Michael Sars Centre at the University of Bergen.

“We didn’t have clear expectations of what we would see in the cultures before putting them under the microscope, but when we did, it was very exciting.”

Multicellularity is a defining characteristic of all animals, enabling them to interact with their environment in unique ways by integrating the input of highly specialized cell types, such as neurons and muscle cells.

For choanoflagellates, flagellated bacterivorous organisms found in marine and aquatic environments all over the globe, the boundary between uni- and multicellularity is less distinct.

Some species, including Salpingoeca rosetta, exhibit complex life cycles that include colonial stages.

While the colonies are formed through cell divisions, much like the developing embryos of animals, they lack specialized cell types and are more akin to a group of individual cells than a cohesive organism.

“Salpingoeca rosetta is a powerful model for investigating the emergence of multicellularity during animal evolution,” said Dr. Pawel Burkhardt, also from the Michael Sars Centre at the University of Bergen.

“Since our study reveals that colonial choanoflagellates coordinate their movements through shared signaling pathways, it offers fascinating insights into early sensory-motor systems.”

Using a newly-developed genetic tool that enables visualization of calcium activity in Salpingoeca rosetta, the authors found that the cells synchronize their behavior through voltage-gated calcium channels, the same type of channels used by animal neurons and muscle cells.

“This evidence of how information flows between cells in choanoflagellate colonies demonstrates cell-cell signaling at the cusp of multicellularity,” Dr. Colgren said.

“Strikingly, the discovery suggests that the ability to coordinate movement at the cellular level predates the first animals.”

The team now plans to further investigate how signals propagate between cells and whether similar mechanisms exist in other choanoflagellate species.

“The tools developed and findings from this study open up a lot of new and interesting questions,” Dr. Colgren said.

“We’re really excited to see where ourselves and others take this in the future.”

A paper describing the findings was published in the journal Science Advances.

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Jeffrey Colgren & Pawel Burkhardt. 2025. Electrical signaling and coordinated behavior in the closest relative of animals. Science Advances 11 (2); doi: 10.1126/sciadv.adr7434