La storia con il testo
NarratorBelow about two hundred metres, sunlight begins to fade. By a thousand metres, it has disappeared entirely. This is the deep sea, the largest habitat on Earth, and one of the least explored. We have mapped the surface of Mars in more detail than much of our own ocean floor.
NarratorConditions here are extreme. The temperature hovers just above freezing, and the pressure is crushing. At the bottom of the Mariana Trench, almost eleven kilometres down, it is more than a thousand times greater than at the surface.
NarratorAnd yet the deep sea is far from empty. In the absence of sunlight, many of its inhabitants make their own. In one large study, roughly three quarters of the animals observed in the open deep ocean were capable of producing light. They use it to attract prey, to find a mate, or, in some cases, to confuse predators with a sudden flash.
NarratorFood is scarce. Much of it arrives as marine snow: a slow, constant drift of dead plankton and other organic matter from the waters above. Some animals can survive for months between meals.
NarratorThen, in nineteen seventy-seven, scientists exploring near the Galápagos Islands made a discovery that rewrote the textbooks. Around volcanic vents on the sea floor, they found thriving communities of giant tube worms, clams and shrimp. Their food chain was based not on sunlight but on bacteria that draw energy from chemicals in the hot water. It was the first evidence that complex life could exist without the sun, and it has since changed how we think about where life might be found, perhaps even beyond our own planet.
