Box Jellyfish Swimming Jellyfish That Can Move

Photo: Box jellyfish with tentacles.

Photo: Box jellyfish swimming

TheĀ box jellyfish can achieve speeds of up to 7.5 kmh (4.6 mph) by squeezing its bell and ejecting a water jet through the rear of its body. This is an astounding speed of six meters/second. By comparison, an average human swimmer can only manage 3.2 kph, and the fastest human swimmer was recorded at 8.6 kph. This squeezing action is the pulsating motion often seen in jellyfish. But the box jellyfish is the only one that actively uses its ability to move to hunt for prey, move from place to place and avoid obstacles. Because of their mobility and ability to move away from danger, they are rarely found washed up onshore.