托福口语 Task 4

Today, we're going to talk about a concept in behavioral ecology called 'optimal foraging theory.' This theory suggests that animals have evolved to maximize their energy intake while minimizing the energy spent to obtain food. In other words, they make choices that give them the most benefit for the least cost. Let me give you two examples to illustrate this. First, consider the common shore crab. When searching for mussels, crabs don't just pick any mussel they find. They prefer medium-sized mussels. Why? Because large mussels have thick shells that are hard to crack, requiring a lot of energy and time, while small mussels provide too little meat. Medium-sized mussels offer the best balance between the energy gained and the energy spent. Second, think about the honeybee. When a bee finds a patch of flowers, it doesn't stay until every flower is empty. Instead, it moves to a new patch when the nectar in the current flowers becomes too low. The bee has learned that spending more time on a depleted patch isn't worth the effort, so it moves on to more profitable sources. These examples show how animals make efficient decisions to maximize their survival.