Little ants, big impact


People often like to think that no other creature in the world, and possibly the universe, can compare to the complexities of human society in which we all participate and the rich inner lives that we all lead.

Perhaps in order to better see the big picture, it is best to use a microscope. 

Deby Cassill — or the “Ant Whisperer,” as some of her students call her — studies the secret lives of ants. 

The USF St. Petersburg professor recently presented at TEDxUSF where talked about her fascination with the tiny and deceptively advanced creatures.

“25 years ago … my big research question was focused on social organization,” Cassill said. 

As a graduate student, Cassill observed the social organization of a species and collected quantitative data. Ants, as it turns out, were easier to observe than primates or other social vertebrates.

As she became more familiar with the pint-sized social beings on the other end of the microscope, Cassill said she became curious about certain aspects of ant life.

“I began to wonder about the inequality of the matriarch’s offspring,” Cassill said. 

Cassill said most of the queen ant’s daughters are small, sterile and short-lived -— six to 12 months at the most. The other daughters are large, fertile and long-lived — six to 45 years depending on the ant species. 

The sons, on the other hand, are also large and fertile. They are even more short-lived, often dead at three months. 

“Once the fertile sons and daughters fly away from the matriarch’s home, they mate,” Cassill said. “The sons die within 24 hours after mating, as do most pregnant daughters.”

The proliferation and expansion of a colony rests on the shoulders of the pregnant daughters that find and excavate a suitable home. Once this is done, they can survive for years or even decades. 

Cassill was intrigued by the inequality of the matriarch’s offspring. She dedicated eight years of her research to developing a bio-economic model of inequality to help explain this phenomenon. The model is currently under review with the journal “PLOS ONE.”

“Another reason I study fire ants is that they are an invertebrate as well as a pest species,” Cassill said. “I can set up experiments in which the individuals live or die. That is absolutely not an option for vertebrate species.”

Being able to freely experiment on ants has afforded Cassill the unique opportunity to learn about collective action during a catastrophe such as a flood, drought, famine, invasion or earthquake. 

One experiment, featured on a WUSF video, tests communication in times of crisis and involves assembling ants into a ball. The researcher then throws the ants into the air. Instead of scattering through the air, the ants cling and lock with one another.

Cassill found that every ant plays an important role in keeping the entire colony as scathe-free as possible.

“Individually, the smaller ants do 10 times the work of the larger ants when it comes to hunting for food, fighting an invader or excavating a new home,” Cassill said. “The larger ants provide homeland security. Their job is to protect their matriarch. The smaller ants do all the other jobs needed to keep the mother and the young alive.”

The complex response system isn’t necessarily fair to each ant, but their roles are clearly defined and consistent throughout the colony. 

According to a WUSF article, Cassill likened ant colonies to modern capitalist economies where resources are not evenly distributed, and further asserted that equality between the queens and the workers would not equal prosperity.

“Each individual counts,” Cassill said. “They might not survive equally, but they do survive longer within the family than if they were to go it alone as a solitary individuals.” 

Cassill said personality also affects the behavior of ants, perhaps reflecting human society — 10 percent of ants are “workaholics,” 10 percent are lazy and the other 80 percent are somewhere in between. 

The amount of work ants do plays into how much food and status they receive. The queen, of course, gets the most food and protection. The queen also sees that the ants that don’t pull their weight in the colony are executed. 

Other than work ethic, Cassill finds that ants have personality traits that are different from one another, such as courage and fear. One of Cassill’s experiments involved dropping a ball into a container of ants. Some ants fled from the ball, while others charged to attack. 

The ants that attacked tended to be older, while the ants that fled were more middle-aged. The youngest ants sometimes played possum. 

To this day, Cassill said she is still finding out new and interesting facts about the lives of ants. A recent observation of a queen ant sleeping showed rapid antennal movement (RAM) that Cassill thought might indicate dreaming, just as rapid eye movement (REM) does for humans.

“Ants have opened so many research window and doors,” she said. “I’ll never be bored.”

Neither are her students, apparently. Cassill has an overall rating of 4.6/5.0 on Almost all of her 63 student ratings give her top marks for being the “go-to” professor for getting involved in undergraduate research as well as being a remarkable lecturer.

“Like most people, my first ‘presentation,’ which was as a TA in front of undergraduate students, was terrifying,” Cassill said. “But my desire to tell a good story overcame my fear. I learned quickly to build humor and demonstrations into my lectures.”

Cassill said one of her favorite demos involved a representation of a jellyfish stinger using a condom, string and a sharp pencil. Nobody slept in class during that lesson.

“If a lecture has an element of fun to it, I actually look forward to that lecture too,” she said. “So it’s a win-win.”

As for being the “go-to” professor for undergraduate research, Cassill said she helped designed a curriculum alongside Riedinger-Whitmore to require research methods and science writing as two core biology courses.

“I’m lucky to have lots of research questions and a lab large enough to handle dozens of students each semester,” Cassill said. “My hope is to  infect them with the joy of science.”