Euplotes gigatrox: A Microbe That Transforms Into ‘Supergiants’ and Cannibalizes Its Siblings

A newly discovered protist, *Euplotes gigatrox*, exhibits a dramatic transformation into “supergiants” that cannibalize smaller, genetically identical cells, according to research published May 14 in the *Proceedings of the National Academy of Sciences* (PNAS). The single-celled organism, found in gunk scraped from an aquarium filter in Curaçao, undergoes a size increase of more than double its normal dimensions, a process linked to its unique survival strategy.

How Does the Transformation Occur?

The transformation occurs in stages, as described by Ben Larson, a cell biologist at Rensselaer Polytechnic Institute in Troy, New York, who discovered the microbes. Initially, the cell develops a larger “mouth” and becomes hyperactive, though it is not yet efficient at cannibalism. When it captures a smaller sibling, the cell’s structure rescales, leading to rapid growth into a “supergiant.” This process involves the organism using its hairlike cilia to engulf and consume its smaller counterparts.

“The body plan of the cell rescales, and they grow up to be these just enormous cannibalistic supergiants,” Larson explained.

What Are the Genetic Mechanisms Behind the Change?

Research by Larson and colleagues revealed that up to 42% of *E. gigatrox*’s genes are involved in the transition between its regular and supergiant forms. The supergiants can shrink back to normal size through asymmetric division, producing up to nine normal-sized offspring within 24 hours and up to 16 in 120 hours. Normal size *E. gigatrox* divide just once in 24 hours.

Why Is This Discovery Significant?

The study of *E. gigatrox* could provide insights into the evolution of complex behaviors in simple organisms. Researchers suggest that understanding how such protists regulate size and cannibalism may shed light on the origins of multicellular life.

“Learning how the protists transform may help researchers understand how simple organisms can develop complex behaviors,” the study notes.

What Do Scientists Say About the Implications?

The findings contribute to ongoing discussions about how unicellular organisms adapt to environmental pressures.

As Larson noted, “The giants and the regular-size cells behave differently. Besides the cannibalism, the big cells walk in circles and no longer swim like smaller cells can.” This behavioral shift underscores the profound changes accompanying the size transformation.