การฟัง TOEFL

🎧 บทถอดเสียง

Narrator: Listen to part of a lecture in a biology class. Professor: Today we're going to discuss a fascinating adaptation in certain marine animals: bioluminescence. This is the production and emission of light by living organisms. While many people think of fireflies, in the ocean, bioluminescence is actually more common. Over 75% of deep-sea creatures produce their own light. Why is this so prevalent? Well, in the deep ocean, where sunlight doesn't penetrate, bioluminescence serves several critical functions. For predators, it can be used as a lure to attract prey. The anglerfish, for example, has a glowing appendage that dangles in front of its mouth. For prey species, bioluminescence can act as a defense mechanism. Some squid and shrimp release a cloud of glowing particles to confuse predators, giving them a chance to escape. Additionally, some species use light for communication, such as signaling to potential mates or warning off rivals. Interestingly, the light is produced through a chemical reaction within specialized cells called photocytes. This reaction involves a molecule called luciferin and an enzyme called luciferase. When these combine with oxygen and energy, light is emitted. The color is usually blue or green, because these wavelengths travel farthest in water. So, bioluminescence is not just a beautiful spectacle; it's a vital survival tool in the deep sea.