The study of how animals communicate has been an important topic these last decades. Psychologists are still looking for universal laws on behavior, ergo, those actions and demeanors that can be found in many different species.
The science in charge of studying animals' communication interfaces is zoosemiotics. Inside this science, we also find zoosemantics, which believes all animals are social beings with their own communications, characteristics, and limits. It is throughout these that they display their mood, emotions like fear or happiness, and biological states.
Precisely the differences and similarities between humans and animals are what make zoosemantics such a fascinating science. Whilst men have a double-articulated language, animals articulate a simple system based on reactions to different stimuli.
Animals use their sensitivity and the five senses - smell, touch, sight, hearing, and taste - to both send and receive messages. Hence, they use four communication spheres or systems; the chemical sphere, the optical sphere, the tactile sphere, and the acoustic sphere. These allow them to capture smells and movements, hear strangers getting close, perceive light's intensity. At the same time, through smells, expressions, sounds and movements, they can also send messages to other animals.