an important way that we can look at the interrelationship between different organisms is by looking at this thing called a predator prey relationship the Predator obviously is the organism that eats the prey the prey is the poor thing that that gets eaten now I want you to see I want to show you each of the the graphs or the traces and we'll see how they're interrelated so down here we've got time and this time is usually in years and here we got our population or the number of organisms so let's start by looking at the prey so the prey population is going to increase when the conditions are right so there's plenty of food uh and the Predator level is low and so their population increases because of reproduction and then the population actually Peaks it Peaks because we have an increased number of predators so if you imagine there's there's plenty of food for the Predators well their population's going to increase so as their population increases the prey population Peaks and starts to drop down when there's less food for the Predators the Predator population Peaks and drops down and then they both continue on with this cycle they're interrelated there's number of things in fact probably three things I want you to be able to see first of all they both have the same pattern of Peaks and troughs I want you to also see that there's more prey than there is predators and that's of course because of the uh the inefficiency of the energy transfer through the food chain the other thing is that the Predator graph is delayed behind the pre graph okay so it lags behind both of these are dependent on each other a change in one changes the other so again continuing with our idea about the inter relationship and uh human impact if we impact on one we're going to impact on the other as well