A closer look

Jellyfish are less like actual animals and more like vaguely sentient puddles of saltwater. Because they lack a brain, heart, bones, or complex organs, roughly 95 percent of a jellyfish’s entire mass is just water. If one washes up onto a hot, sunny beach, it doesn't just die—it literally evaporates. After a few hours in the baking sun, there will be virtually nothing left on the sand except a thin, nearly invisible film of leftover biological dust.