How do desert iguanas use ultraviolet-visible scent markers to communicate?

Desert iguanas (Dipsosaurus dorsalis) utilize a specialized chemical communication system for territorial defense that involves both scent and visual cues. Rather than releasing pheromones directly into the environment, these lizards deposit them in an inert carrier compound that prevents the scent from dissipating prematurely.1

These deposited pheromone packets absorb ultraviolet light, which causes them to appear as distinct black specks to other iguanas, as these lizards possess the ability to see in the ultraviolet spectrum. This visual signal serves to advertise the presence of the marker to other individuals. Once an iguana detects these specks, it approaches and flicks the carrier with its wet tongue. This action releases the pheromones, allowing the receiver to process the chemical information. This sophisticated method allows desert iguanas to maintain territorial boundaries effectively by combining visual detection with targeted chemoreception.1