Why is there competition or struggle between animals and plants?

It is a struggle that most often occurs between plants and animals. Competition between different kingdoms generally does not take place in the usual sense. Different types of animals can compete for food or territory. Plants can compete for territory and better habitat. The struggle is due to the fact that plants are a food source for many animals. So plants have developed many ways to protect against pests. These are thorns, poisonous leaves and fruits and other devices.