What Nighttime Jellyfish Don’t Want You to See: Science Explains Why They Can’t Swim Like Other Creatures!

Sun, 03 May 2026 17:01:25 +0000

What Nighttime Jellyfish Don’t Want You to See: Science Explains Why They Can’t Swim Like Other Creatures If you’ve ever glimpsed translucent jellyfish gliding silently through dark ocean waters at night, you might have been captivated by their elegance—until you learn they can’t truly swim like fish or other marine animals. The haunting beauty of jellyfish masks a fascinating biological limitation that scientists are only beginning to understand. In this article, we dive into the science behind why nighttime jellyfish lack conventional swimming ability, revealing the surprising reasons behind their mesmerizing but awkward movement. ### The Illusion of Graceful Movement Nighttime jellyfish are often seen drifting and pulsing through the water with a dreamlike motion, their gelatinous bodies swaying with minimal effort. To the human eye, this motion appears effortless and fluid—almost lifelike. But beneath this serene surface lies a radical truth: jellyfish don’t swim. Unlike fish, squid, or even sea turtles, they lack proper propulsion mechanisms. Instead, their movement relies on passive drifting powered by rhythmic contractions of their bell-shaped bodies. While this may look like swimming, biologists classify it as pulsed jet propulsion—a fundamentally different and less efficient method.