TOEFL iBT Training - Integrated Writing During the lecture, the man told about sea otters and three hypothesis was developed to explain the decline of population. The first was the predator hypothesis, during the listening we discovered that the pollution kills many kinds of animals in the middle of them, were the sea otters. This point was mentioned in the passage how the principle cause to sea otters' death. The scientists discovered many evidences indicate that oil rigs have chemical substancies that change the immune system of this animals. The second hypothesis was that orcas whale eat this kind of animals because they are available, others animals was dead transforming the sea otters in their target. Finally, the third indicates that this animals lives in easy places to orca's access and kill them. These points about orcas were just mentioned in the text, because they believe that isn't the most important motivation to the fact that today the population is less than many years ago.