Why Ants Defy Gravity: The Science of Surface Area vs Volume

Ants are astonishing creatures; they can lift objects up to 50 times their own weight, work together seamlessly, and reproduce rapidly across the globe. Even more staggering, the number of these strong‑jawed lift‑workers exceeds the human population by more than a million times.

First, recall a principle: when an object's linear dimensions increase, its surface area grows faster, and its volume grows even faster than its surface area.

This means that large‑volume objects (such as a human body) are “heavier inside,” while each unit of surface area is relatively “larger.” Compared with their tiny internal volume, an ant’s body has a very large surface area.

What does a larger surface feel like? First, it means you no longer need to fear heights.

When you fall from a great height, two forces compete like a tug‑of‑war: downward gravity and upward air resistance. Gravity acts on mass, so its magnitude is linked to your internal weight; air resistance acts only where air contacts you, so its magnitude depends on your body’s surface area.

Simply put, your weight accelerates your fall, while your surface area slows it down. This explains why a thrown brick falls straight, a thrown piece of paper drifts, why penguins cannot fly, yet eagles can.

Humans are like bricks and eagles: heavy with relatively small surface area. When we fall from great heights, our terminal speed can reach about 193 meters per second, a result that would be catastrophic.

In contrast, ants are like paper and eagles: large surface area and tiny weight. Their maximum falling speed is only about 6 km/h. Theoretically, an ant could simply walk away from a high‑rise drop without danger.

You might wonder whether a larger surface would eliminate the need for parachutes—interesting, but not so simple; ants also face challenges, one being a fear of water.

Water’s surface tension causes molecules to cling together, creating a thin film that can trap ants. When an organism leaves the water, a half‑centimeter‑thick water layer remains attached by surface tension. For humans this weight is negligible, but for an ant the same film can be comparable to or even ten times its body weight, making water a potentially lethal hazard.

Source: Ben Orlin, translated by Tang Yanchi, “Math for the Curious: A Delightful Introduction to Mathematics with Playful Illustrations.”