How do animals use visual signals to communicate?

Animals use visual signals to communicate by creating controlled perturbations of the environment that can be detected and recognized by others. These signals often evolve through ritualization, a process where existing body structures, movements, or physiological processes are exaggerated and simplified to enhance their visibility and clarity.123

Mechanisms of Visual Signaling

• Movement and Posture: Animals often use simple muscle movements to signal, such as staring, baring teeth, or changing body orientation. These "intention movements" provide cues about future actions, such as attacking, mating, or fleeing.21
• Coloration and Contrast: To catch a receiver's attention, animals increase the contrast between a signal body part and the background. This is achieved through black-and-white patterns (using melanins) or vibrant colors derived from carotenoid pigments or structural techniques that scatter light.1
• Bioluminescence: In environments with little ambient light, some animals, such as fireflies and deep-sea fishes, produce their own light chemically to signal for mates or deter predators.145

Visual signals are essential for courtship, species recognition, and conflict resolution, often evolving to exploit the specific sensory biases of receivers.235