Living World / Unusual Organisms

Tschinkel made his first cast in 1985—a nest of fire ants, known as Solenopsis invicta, meaning “the unvanquished.” They create huge, long-lived colonies with a quarter of a million individuals, and queens that live for seven years. While most ants defend only their nests, fire ants ferociously defend surrounding territory, too, often over 1,000 square feet, and their stings are memorable even to mammals. Tschinkel had completed groundbreaking studies revealing “the behavioral rules governing the flow of food” in their colonies. He had explored their nests—first chloroforming the inhabitants, partly for his own safety but mostly “to knock them down where they stood so I could see how they were distributed in the nest”—and thought he had a good idea of the nests’ geometry. But when he poured dental plaster into one and then dug it out, the picture was much clearer. “The nests of fire ants are a lot more patterned and less randomly arranged than I had thought,” he says. “They were obviously organized, regular, predictable—so interesting. I got into the architecture.”

A few years later, he cast the nest of Odontomachus brunneus, the trap-jaw ant, named for its unusual facial structure. The trap-jaw’s gigantic mandibles protrude to the sides, giving it the look of a hammerhead shark. The jaws are remarkably strong: If the ant clamps something too smooth and round to hold on to and its jaws slip off, they snap shut with enough force to shoot the ant three inches backward. In this cast, Tschinkel recognized the same construction he’d seen in the fire-ant nest, “only here the internal nest consisted of a single unit—the shish-kebab unit.” That is Tschinkel’s description of chambers strung one after another along a single vertical tunnel, giving the cast itself a lumps-along-a-stick appearance. “So I got the idea of a basic, widespread architectural unit that might be fundamental to many ant nests.” 

Fire-ant nests are shallow; most of the chambers are linked closely to the core near the surface and come out of the ground pretty much intact. But the trap-jaw ants had built more of a sprawling nest, one that would lose real character—and data—if it was incomplete. Tschinkel had to retrieve all the pieces, and to see it whole, he had to devise a way of gluing and supporting an entire reassembled cast.

He was still pondering the problem when he got interested in the Florida harvester ant—Pogonomyrmex badius, casually known as the pogo. One of the more impressive ant species, the harvester constructs an elaborate, seven-foot-deep nest in less than a week, moving pounds of sand in the process. Then foragers search their territory for seeds, which are stored—as many as 300,000 of them—in subterranean chambers. Workers crush the seeds into pulp and feed it to the larvae. In turn, Tschinkel thinks, the larvae probably return a nourishing liquid to the workers, supplementing their diet of sweet plant exudates, aphid honeydew, and juices sucked from prey insects. Tschinkel’s early attempts to clearly describe the areas in the nests where all this happens were unsuccessful. But in the early 1990s, he found a freshly abandoned pogo nest, and he filled the entire thing with a single five-gallon pour of dental plaster. Once the plaster hardened, the cast came out of the ground—in 180 pieces.

“I cleaned them up, and they sat on my lab bench for three or four years,” he says. “Assembling it seemed daunting.” But Tschinkel, a hobby woodworker whose house is filled with elegant handmade furniture of his own design, devised a method of gluing the broken casting together with epoxy and mounting the cast in front of a tall plywood backboard, supporting it with projecting steel welding rods so that it would hang in space in the same orientation it occupied in the ground. “I started assembling subunits on the lab table,” he says, and over months—many times longer than it took the ants to build the nest—“I reassembled the cast into perhaps a dozen subunits and then figured out how these went together.” The nest of the harvester colony has 130 chambers connected by about 30 feet of vertical tunnels.

He did the same with other species, including Aphaenogaster ashmeadi and Pheidole morrisii, and some of those mounted casts occupy Plexiglas cases outside his office on the Florida State campus. They are, as Tschinkel describes them, “physically, intellectually, and aesthetically pleasing.”