agonistic behavior is say animal behavior. When two animal are fighting for one source of food or territory, they will compete with each other, but they wouldn't hurt each other, and the weaker one would just leave after the front. After the fight, the professor uses rattlesnake as an example. It is a kind of small, small snake that lives on the ground. So for example, when two snakes are fighting for a same hall for living, and they are some food in that hall, they will stand up and this their body and face each other to fight. So they will pretend that they were really tall and push each other. After the fight is finished. The winner would have the chance to buy it another, but it wouldn't do it, it will just release the loser one.