Why are some animals so brightly colored?

The answer

Bright coloration in animals serves two main opposing purposes. Aposematic (warning) coloration advertises toxicity or danger, as seen in poison dart frogs whose vivid reds, blues, and yellows signal lethal skin toxins to predators. This honest signaling benefits both parties: predators learn to avoid a painful lesson, and the prey survives. In contrast, sexually selected coloration, like the peacock's iridescent tail, evolves through mate choice. Females prefer more elaborate ornaments because they signal good genes, health, and the ability to survive despite a conspicuous handicap. Some species combine both strategies; the male mandrill's vivid face coloration signals both dominance rank to rivals and fitness to potential mates. The genetics and development of these color systems involve complex interactions between pigment cells, structural nanoarchitecture, and hormonal signaling.