TOEFL Speaking Task 3

In biology, organisms often develop traits that appear to benefit other species rather than themselves. This phenomenon, known as mutualism, involves a close and long-term interaction between two different species where both derive a benefit. Mutualistic relationships can be obligatory, where one or both species cannot survive without the other, or facultative, where the interaction is beneficial but not essential for survival. The key aspect is that the interaction increases the fitness of both participants, often through resource exchange or protection.

Professor: Let me give you a classic example from my own research on coral reefs. The clownfish and the sea anemone share a mutualistic relationship. The anemone has stinging tentacles that would normally kill small fish, but the clownfish has a special mucus coating that protects it from the stings. So the clownfish lives safely among the anemone's tentacles. In return, the clownfish acts as a lure, attracting larger predators like butterflyfish, which the anemone then stings and eats. Additionally, the clownfish's movements create water circulation that brings oxygen to the anemone, and it also cleans the anemone by eating dead tentacles. Neither species could thrive as well without the other – the clownfish would be vulnerable to predators, and the anemone would struggle to capture food and get enough oxygen. This is a clear case of both species benefiting from their interaction.