Alligator Death Roll: A Story of Shear Force Large Prey Cannot Resist

Picture the scene: A thirsty wild hog steps out from the cover and protection of the woods to the swamp’s shore. It begins to lap up the water when, from under the dark waters, emerges a 500-pound alligator. Before the hog can turn and run, the alligator has already opened its powerful jaws, clamped them down around its thick neck, and dragged the pork dinner into the water. During its fight for life, the hog attempts to pierce the alligator’s scutes with its tusks, but to no avail. The alligator—unable to chew—employs its deadliest and most effective hunting technique: the death roll. It begins a series of repeated 360-degree rolls, and the hog is both drowned and shredded into smaller, bite-sized pieces.

The death roll is one of the most fascinating aspects of alligator behavior. This hunting technique perfectly aligns with their design as apex predators. First, despite their many conical teeth, not one is a molar. Alligators, therefore, cannot chew their meals; they gulp them down. They also do not have sharp front canines like lions, so they cannot rip chunks of meat from the bone. The force of the death roll shreds their meals into bite-sized pieces.

Second, the speed and force of the death roll disorient the alligator’s prey, making it nearly impossible for the animal to fight back or escape. While the prey become dizzy and confused—much like people do when spun several times before being pushed toward a piñata—alligators seem immune to the disorientation they unleash on their meals.

Alligators also deploy this behavior defensively as a wrestling move to demonstrate dominance over other alligators in fights over territory or potential mates.

Do All Alligators Death Roll?

Alligators belong to the order Crocodilia, which is composed of semiaquatic, predatory reptiles known as crocodilians. The order includes both extant species of alligators (American and Chinese) and all species of crocodiles, gharials, and caimans.

In a 2019 research study by paleontologist Dr. Stephanie Drumheller-Horton from the University of Tennessee, Knoxville, 25 species were studied at the St. Augustine Alligator Farm in Florida. Kent Vliet from the University of Florida and Jim Darlington, curator of reptiles at the St. Augustine Alligator Farm, assisted in the study.

Animals were prompted to death roll using two methods of stimulation: a feeding cue and an escape cue. The feeding cue involved presenting each animal with a bait item, to which resistance would be applied during a biting event. The second cue involved capturing each animal with a rope or catch pole, a standard technique for capturing crocodylians, but one that also often prompts an attempt to escape.

Drumheller, S. K., Darlington, J., & Vliet, K. A. (2019). Surveying death roll behavior across Crocodylia. Ethology Ecology & Evolution, 31(4), 329-347. https://doi.org/10.1080/03949370.2019.1592231

The results showed that every species but one exhibited the death roll behavior. Paleosuchus palpebrosus, known as the Cuvier’s dwarf caiman, a small crocodile species from South America, did not. However, just because it did not perform the behavior during the experiment does not mean that it cannot. Previously, it was believed that some species, particularly those with long skinny snouts like the Indian gharial, do not use this behavior. It turns out they do—for feeding, establishing dominance, and competing for females.

While alligators prefer life in the water, alligators are semiaquatic and do utilize this behavior on land. They can run in short bursts up to 10-20 miles per hour on land but can swim at speeds closer to 20 miles per hour, which can make them far more effective hunters in the water. Nevertheless, when the occasion arises on land—whether for a meal, mate, or menace—alligators will employ the death roll.

What’s the Science Behind the Death Roll?

In 2007, researchers conducted a detailed analysis of the death roll, also called twist or rotational feeding. They used juvenile American alligators (mean length = 0.29 meters) to measure shear force at the snout. The researchers then extrapolated the data to develop a mathematical equation to estimate what the shear force a three-meter alligator would produce.

The researchers recorded these tiny alligators and observed that alligators tuck their feet into their bodies and bend their tails and heads to form a “C” shape to shift their inertia—much like a figure skater who draws her arms toward her body to increase the speed of the spin. Additionally, as an alligator grows, the amount of shear force it produces increases exponentially. “Shear forces generated by the spinning maneuver are predicted to increase disproportionately with alligator size, allowing dismemberment of large prey,” they concluded.

In other words, as the writer of Science Made Cool explains, “Rolling works because muscles and tendons are strong in tension, but weak in torsion. Pull on flesh, and it resists that tensile force. Twist it, and it tears much sooner. So when an alligator latches on to a deer and rolls, it’s using the deer’s own mass against it. The roll may produce a huge force, but a small animal just rolls along with the gator. A larger animal, weighed down by its own tissues, resists the torque and gets torn apart.”

Alligators use this brute-force hunting technique on a variety of prey, including fish, snakes, raccoons, muskrats, nutrias, deer, and wild boars, to name a few. The study by Dr. Drumheller-Horton demonstrated that not only large crocodilian species employ the death roll, although it was once understood to be a larger crocodilian’s go-to tactic. Alligators are opportunistic eaters, so they will consume whatever they can get their jaws on and will discharge the death roll if the size and resistance of their prey warrant it.