What is the relationship between a predator and a prey? Two predator with the same prey?

A predator is an organism that kills and feeds on other organisms. The organisms that are eaten are called prey. An increase of population of prey means more food for the predator. Subsequently, an increase number of predators. The increase number of predators will lead to the decrease of prey, due to the fact that the prey are consume by the predators. After a while, the number of prey increase again, because the number of predator decrease due to the lack of food. Sometime, a prey has to predator. The decrease of the population of the prey will affect the population of the two predators, causing them to be dependable on their other source of food.