Single-celled organisms aren't usually thought of as dramatic. With no organs, nervous systems, or complex bodies, they often seem like the simplest forms of life imaginable. But a newly discovered microbe from the Caribbean island of Curaçao is challenging that assumption in spectacular fashion. Researchers from the Rensselaer Polytechnic Institute (RPI) have identified a species that can transform into a giant cannibalistic version of itself, abandoning its usual diet to stalk, capture, and devour its own relatives.
The discovery, published in the Proceedings of the National Academy of Sciences (PNAS), suggests that even a single cell can undergo surprisingly complex developmental changes, features scientists have traditionally associated with animals.
"This is a single cell doing something we usually associate with the development of animals," said study author Ben Larson, assistant professor in the Department of Biological Sciences at RPI, in a press release. "It expands our picture of what single-celled organisms are capable of, and gives us a new system for asking questions about how cells control their form and function.”
Inconspicuous Cells Transform into Giant Cannibals
The single-cell organism, named Euplotes gigatrox, was discovered inside a seawater filtration system on Curaçao. It belongs to a group of microscopic organisms known as ciliates, which typically feed by filtering bacteria from the water.
Most individuals follow that script. But researchers found that a small fraction within a clonal population (every cell has the same DNA) spontaneously transforms into oversized "supergiants" that are more than twice as long as their normal counterparts. These enlarged cells develop broader bodies, larger mouths, and a very different appetite.
Instead of grazing on bacteria, the supergiants become predators. They actively hunt smaller members of their own population, swallowing them whole at a pace of around one victim every 10 minutes. But the makeover doesn't stop there. Usually, the cells both swim and crawl, but supergiants largely give up swimming. They move in looping patterns across surfaces, a behavior better suited to tracking down prey.
"Supergiant formation represents a tradeoff," said Larson. "These cells become better hunters but worse swimmers, shifting their trophic niche from feeding on bacteria to exploiting a completely different type of prey."
Read More: Cannibalism in Snakes Is Not Uncommon — but Could be a Behavior That's Tied to Evolution
Cannibalism Might Just Be a Phase
To understand what drives the transformation, the team examined which genes were active in normal cells, supergiants, and cells that had reverted back to their ordinary form.
According to their analysis, supergiants aren't simply oversized versions of the same organism. Instead, they appear to represent a distinct life stage, with major shifts in cellular activity affecting reproduction, protein production, and other internal processes.
Even cells that returned to their normal state retained a unique molecular signature. Interestingly, these reverted cells were less likely to produce new supergiants, suggesting the organism has built-in mechanisms that temporarily suppress the transformation.
Survival Strategy During Scarcity
The cannibalistic giants tend to appear when food becomes less plentiful, and populations stop growing rapidly, a common driver of cannibalism within more complex animal populations as well. Yet they never make up more than about five percent of the population. Researchers believe this may be a form of biological risk management, with a small number of cells switching strategies to exploit a different food source when conditions change.
Beyond the unusual behavior itself, the discovery gives scientists a rare opportunity to study how development works in a single-celled organism.
"Most of what we know about development comes from animals," Larson said. "We now have a system where we can study those same fundamental questions, as analogous developmental processes play out in a single-celled organism on a completely different branch of the tree of life."
Read More: Ancient Humans May Have Turned to Cannibalism For A Deeper Meaning
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Proceedings of the National Academy of Sciences (PNAS): Regulated development of cannibalistic supergiant cells in the ciliate Euplotes gigatrox
