The Stentor, a giant in the world of single-celled creatures, is a trumpet-shaped organism that ranks among the largest of its kind, stretching to the size of a sharp pencil tip. Despite its impressive size, the Stentor sometimes struggles to capture the swimming bacteria and microscopic algae it feeds on.
A recent study reveals that Stentors, part of the Protist group, have found a way to overcome this challenge by adopting a “family style” approach to feeding. In a paper published in the journal Natural Physics on Monday, scientists shared their discovery that Stentor colonies can create currents to draw in prey more efficiently.
These new findings suggest that Stentors are capable of cooperation despite lacking neurons and brains.
“These single-cell organisms exhibit behaviors that we typically associate with more complex life forms,” said Shashank Shekhar, a biophysicist at Emory University and lead author of the study. “They form these higher structures, much like we do as humans.”
Scientists believe that the ability of single-cell organisms to form groups is a critical step in the evolution towards multicellular life on Earth. Recent discoveries emphasize the role of physical states and predator-prey interactions in these cellular collaborations.
In their natural habitat, Stentors are commonly found near the surface of ponds. They have cilia at the wider ends of their bodies that wave in patterns, creating water streams to capture prey.
To observe these currents in a laboratory setting, Dr. Shekhar placed a drop of milk in a Petri dish with a Stentor and watched the fluid movements under a microscope. “You can see them creating swirls around their mouths,” he described, likening it to the swirling cosmos in Van Gogh’s “Starry Night.”
When food is abundant, Stentors often come together in clusters, but little research has been done to explore the reasons for this colony formation.
Dr. Shekhar and his team observed the interactions between pairs of Stentors by analyzing microscope video footage of the organisms in a Petri dish capturing food particles to measure liquid dynamics.
The video unveiled intriguing patterns as the Stentors were drawn towards each other before moving apart, resembling a magnetic repulsion. “They seem to oscillate between ‘I like you’ and ‘I don’t like you,'” explained Dr. Shekhar.
Further analysis revealed that Stentor pairs often had unequal connections, with one organism producing stronger currents. When they gathered, the combined streams benefited both creatures, allowing weaker Stentors to benefit from the stronger ones.
These dynamics among Stentors lead to what Dr. Shekhar terms “indiscriminate behavior.” By forming colonies and choosing stronger partners, Stentors enhance their feeding efficiency, increasing the overall flow rate and enabling them to capture prey faster and from greater distances, ultimately boosting nutrient intake for the group.
The grouping behavior of single-cell organisms like Stentors to enhance survival represents a crucial stage in the evolution towards multicellularity. Uniting against single-cell prey makes them more formidable as predators, prompting vulnerable prey to band together for survival.
According to evolutionary biologist William Ratcliffe from Georgia Tech, who was not involved in the study, the improved feeding efficiency of group predators like Stentors can drive the evolution of multicellularity in prey organisms. “As a single cell, you’re vulnerable to being consumed. But as part of a larger group of cells, you become a less appealing target for predators,” Dr. Ratcliffe explained.
These new discoveries underscore the significance of physical forces in shaping biological evolution.
“While we often focus on genes and chemicals, the role of physics in the development of multicellular life is equally important,” noted Dr. Shekhar. “Even simple factors like water flow can influence evolutionary pathways.”
Source: www.nytimes.com
