托福口语 Task 3

In biology, the term 'commensalism' describes an ecological relationship between two species in which one benefits while the other is neither helped nor harmed. This interaction is distinct from mutualism, where both benefit, and parasitism, where one organism is harmed. Commensalism often involves one species using another for transportation, shelter, or access to food resources, without affecting the host’s survival or reproduction.

Professor: Let me give you a classic example from marine biology. Consider the remora fish, which has a specialized suction disk on its head. The remora attaches itself to a large shark. As the shark swims and feeds, it scraps off bits of its prey, leaving scraps behind. The remora then detaches and eats these leftover food particles. Now, does the shark benefit? No. But does the shark suffer? Actually, no. The remora does not harm the shark’s flesh or impair its movement. The shark simply continues its normal behavior. So the remora gains food and easy transportation, while the shark is unaffected—neither helped nor harmed. This perfectly illustrates commensalism.