Mysteries of the Microbial: Unraveling the Electric Choreography of Choanoflagellates

Researchers at the University of Bergen have discovered an astonishing variety of behaviors within the rosette-shaped clusters of Salpingoeca rosetta, an uncommon species of choanoflagellate — the nearest ancestors of animals.

“We observed communication among the cells within the colonies, which regulates shape and ciliary movement throughout the rosette,” stated Dr. Jeffrey Colgren, a scientist with the Michael Sars Centre at the University of Bergen.

“We did not have definite expectations of what would be observed in the cultures prior to examining them under the microscope, but upon doing so, it was extremely thrilling.”

Multicellularity is a distinguishing trait of all animals, allowing them to engage with their surroundings in distinct manners by integrating the contributions of highly specialized cell types, such as neurons and muscle cells.

For choanoflagellates, flagellated bacterivorous entities inhabiting marine and freshwater ecosystems globally, the distinction between uni- and multicellularity appears less clear-cut.

Certain species, including Salpingoeca rosetta, showcase intricate life cycles that incorporate colonial phases.

Although the colonies form through cellular divisions, resembling the developing embryos of animals, they do not possess specialized cell types and are closer to a collection of individual cells than a unified organism.

“Salpingoeca rosetta serves as a compelling model for probing the emergence of multicellularity during animal evolution,” remarked Dr. Pawel Burkhardt, also from the Michael Sars Centre at the University of Bergen.

“As our study reveals that colonial choanoflagellates coordinate their movements using shared signaling pathways, it provides intriguing perspectives on early sensory-motor systems.”

Utilizing a newly developed genetic tool that allows for visualization of calcium activity in Salpingoeca rosetta, the researchers uncovered that the cells synchronize their actions through voltage-gated calcium channels, which are the same channels utilized by animal neurons and muscle cells.

“This evidence of how information travels between cells in choanoflagellate colonies highlights cell-cell signaling at the threshold of multicellularity,” Dr. Colgren remarked.

“Remarkably, the finding implies that the capacity to coordinate movement at the cellular level predates the first animals.”

The team intends to further examine how signals travel between cells and whether analogous mechanisms are present in other choanoflagellate species.

“The tools developed and insights gained from this research raise many new and fascinating questions,” Dr. Colgren stated.

“We are truly enthusiastic to see where we and others will take this in the future.”

A study detailing the findings has been 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