The fastest animal for its body size probably isn't what you'd expect

Cheetahs may be fast, but that's just because they're big.

animal body clocks
Body clock.Illustration by Goran Factory

What’s the fastest animal on Earth? Depends on how you define quickness. By simple miles per hour, classic megafauna like cheetahs dominate the leaderboard. But if we measure velocity by the body lengths an animal travels per second, those quick cats have some competition. This race of proportions allows contenders from all kingdoms to go for gold. Here’s how a cross-section of critters achieves top speeds.

1. Common squid

Jet propulsion
This cephalopod shoots through the ocean like a tentacled jet. It sucks water into a chamber in its 8-inch-long cone-shaped body, then contracts its muscles to push the liquid through a narrow ­funnel-​shaped organ near its head. The flow blasts in one direction, launching the adult squid's gelatinous form the opposite way at 10 body lengths per second.

2. Cheetah

Speeding spines
Famous for sheer giddyup, these spotted cats' flexible spines give their limbs a wide range of motion. The stretch maximizes stride and allows acceleration from zero to 60 mph in three seconds. Hind legs dense with fast-twitch ­fibers—​ a powerful type of ­muscle—​­enable 70 mph bursts. But factor in body size, and they fall behind: 23 lengths per second.

Hummingbird

Dive for love
Hummingbirds pump their wings in a figure eight so quickly that humans see only a blur. To impress the ladies, 4-inch-long male Anna's hummingbirds accelerate faster than any other vertebrate relative to body size—including fighter pilots. Suitors fly at 385 body lengths per second during their customary courtship dive, all powered by outsize pecs.

Copepod

Mighty legs
Where there is water, there are ­copepods serenely floating. In times of crisis, the ­torpedo-​­shaped 1-millimeter crustaceans can accelerate to 500 body lengths per second. Two kinds of limbs—some vibrating oars for swimming and some stronger legs for jumping—allow the creature to blast over 20 inches, perfect for escaping a fish's gaping jaws.

This article was originally published in the Spring 2019 Transportation issue of Popular Science.