Aposematism refers to:
Aposematism is the use of conspicuous signals that advertise an organism's defenses to potential predators. Bright red, orange, yellow, or contrasting black patterns can become associated through predator learning with toxins, distastefulness, stings, spines, or other costs of attack. Once learned, avoidance benefits both prey and predator by reducing harmful encounters. Background matching instead reduces detection and is cryptic coloration. A harmless species resembling a defended model is Batesian mimicry, while a sudden flash may startle or redirect attack without functioning as a persiste
Ref: Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10
