Euprothes Gigatrochus, a newly identified species of ciliate organisms, found in a seawater filtration system on the Caribbean island of Curaçao, exhibits the potential to develop into cannibalistic “supergiants.” This discovery raises intriguing questions about the complexity of microscopic life.

“Ciliates of the genus Euprotes have captivated researchers since the advent of microscopy due to their widespread presence and unique characteristics,” stated lead author Dr. Ben Larson from Rensselaer Polytechnic Institute and colleagues.

The genus Euprotes is prevalent in various aquatic ecosystems and has been extensively studied concerning their movements, mating rituals, symbiotic interactions, distribution, and adaptations to environmental conditions.

These ciliated cells possess a highly structured and complex animal-like morphology, featuring cilia organized into membranous cells that are specialized for feeding (by generating water currents), swimming, and moving across substrates.

Among these organisms, Euprothes Gigatrochus was recently collected from a seawater filtration system in Curaçao.

In clonal populations, where all cells contain identical DNA, some cells can spontaneously evolve into supergiant forms, exceeding normal cell lengths by more than twofold, characterized by broader bodies and larger mouths.

Supergiants transition from filtering and consuming bacteria to becoming predatory hunters, capturing smaller cloned relatives at a remarkable rate of one every ten minutes.

“This single-celled organism exhibits behaviors typically associated with multicellular development,” Dr. Larson remarked.

“This expands our understanding of the capabilities within single-celled organisms and provides a new framework for investigating how cells regulate their form and function.”

The researchers assert that the behavioral adaptations extend beyond feeding.

Normal cells navigate surfaces and gracefully swim along spirals, while supergiants employ a distinct circular locomotion suitable for hunting prey, awkwardly rolling when displaced from surfaces.

“Supermacrogenesis is a strategic trade-off; while these cells excel at hunting, they sacrifice swimming efficiency, thus shifting their dietary focus from bacteria to larger prey,” Dr. Larson explained.

To delve into the molecular basis of these transformations, the authors sequenced transcriptomes from Euprothes Gigatrochus normal cells, supergiant cells, and those reverting from supergiant stages.

The findings reveal that supergiants represent distinct developmental stages, showcasing significant variations in gene expression related to cell cycle control, protein synthesis, and membrane organization.

Cells reverting from the supergiant state display distinctive molecular profiles that temporarily inhibit pathways driving transformation.

Populations derived from recently reverted cells exhibit a slower emergence of new supergiants compared to those initiated from normal cells, regardless of external conditions.

Supergiant cell formation typically occurs as populations transition from rapid growth to a stationary phase, particularly in the absence of small prey. They remain present only as long as small prey is scarce and larger ones (normal cells) are available.

Supergiants constitute no more than 5% of the population, which aligns with a bet-hedging strategy where a minority of cells explore alternative resources.

This groundbreaking discovery offers a fresh perspective on the development of unicellular organisms, which must execute cellular and organism-level functions within a singular membrane.

“Most of our developmental knowledge is derived from multicellular organisms,” Dr. Larson noted.

“Similar developmental processes are at play in single-celled organisms across various branches of the tree of life, paving the way to study fundamental biological questions in new contexts.”

The details of this study will be published in Proceedings of the National Academy of Sciences.

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Ben T. Larson et al. 2026. Controlled development of cannibalistic supergiant cells in ciliates. Euprothes Gigatrochus. PNAS 123 (20): e2606891123; doi: 10.1073/pnas.2606891123