Iridescent

Vertebrates

The feathers of birds such as kingfishers, birds-of-paradise, hummingbirds, parrots, starlings, grackles, ducks, and peacocks are iridescent. The iridescence is created by ordered arrays of melanosomes within feather barbules; also hollow melanosomes, which are largely restricted to birds, enhance colour brightness by increasing the refractive-index contrast between melanin, keratin, and the air-filled central cavity of the organelle. The lateral line on the neon tetra is also iridescent. A single iridescent species of gecko, Cnemaspis kolhapurensis, was identified in India in 2009. The tapetum lucidum, present in the eyes of many vertebrates, is also iridescent. Iridescence is known to be present among prehistoric non-avian and avian dinosaurs such as dromaeosaurids, enantiornithes, and lithornithids. Muscle tissues can display irisdescence.