Animals that are territoiral, defend other animals that have a nest, mating site, or den. It is rare for the defense to cause a fight. To get food for their family, they defend their territory. Most times you can tell where an animals territory is. It can be visual or olfactory.
These tigers are fighting for a territory.
The cat is showing visual display of having a territory.
This hippo is also showing visual display over territorial display.
http://www.wisegeek.com/what-is-a-hippopotamus.htm http://animals.desktopnexus.com/wallpaper/1196709/ http://www.vcahospitals.com/main/pet-health-information/article/animal-health/aggression-introduction-to-aggressive-behavior/129
Communication is a form of behavior that sends a signal to another organism. It can be facial expressions, gaze, gestures, or chemical signals. Bees, termites, and ants use pheromones. Pheromones are a chemical signal sent from one organism to another to convey a message.