托福口语 Task 4

Today, I want to talk about a fascinating concept in animal behavior called 'biological rhythms' — specifically, how some animals have evolved to synchronize their activities with the lunar cycle. One key example is the grunion fish, which lives off the coast of California. These fish time their spawning to occur on the highest tides of the spring, which happen right after a full or new moon. The females ride the waves onto the beach, bury their eggs in the sand, and then the males fertilize them. The eggs develop in the sand for about two weeks, and when the next set of high tides arrives — again aligned with the moon — the hatchlings are washed out to sea. A second, very different example is the coral reefs. Many species of coral release their eggs and sperm into the water on the same night, often a few days after the full moon. This mass spawning event is synchronized across the entire reef, ensuring that eggs and sperm meet in the water. The trigger seems to be the moonlight itself, which helps corals coordinate their reproductive timing.