Marine scientists have discovered a previously unknown jellyfish species emitting a natural glow in total darkness nearly 4,000 meters below the ocean surface. At such extreme depths, sunlight never reaches—yet this jellyfish uses bioluminescence, likely for communication or defense. The find highlights how little of Earth’s deep oceans have been explored. Key Facts: • Discovered at ~4,000 meters depth • Lives in complete darkness • Produces natural bioluminescent glow • Found during deep-sea ex