Quick Answer
The animal most associated with rainbow colors is the mandrill, a primate species found in tropical rainforests of West Africa. Male mandrills have bright colorful faces and rumps with hues of blue, red, yellow, green and purple. This serves to attract mates and intimidate rivals. Other rainbow colored animals include birds like parrots, hummingbirds, and birds-of-paradise, as well as reptiles like the rainbow boa and panther chameleon. Some aquatic animals also display iridescent rainbow colors, like tropical fish.
In the natural world, coloration serves many important purposes for animals. Camouflage helps prey animals blend into their environments and avoid predators. Warning coloration advertises toxicity or foul taste. Mimicry allows harmless species to impersonate dangerous ones as protection. Displaying bright, vivid colors is one strategy animals use to attract mates, recognize their own kind, intimidate rivals, and communicate mood or status. While single bold colors like red, yellow or blue are common in the animal kingdom, a rainbow of multicolored hues is rarer and limited to certain species. So which animals actually display the full spectrum of rainbow colors?
The Mandrill
The mandrill is likely the most famous rainbow colored animal. Mandrills are large primates belonging to the baboon family. They are native to the tropical rainforests of West Africa. Most Old World monkeys have drab coloration of grey, brown or olive green fur. But male mandrills have acquired dazzling Technicolor through sexual selection. They sport bright blue ridges on their noses, golden beard hair, crimson lips and rumps striped with yellow, purple, blue and pink bands. This colorful adornment advertises the male’s strength and virility to potential mates. It also serves to intimidate rival males when competing for access to females. The more intense the hues, the higher the male’s social status within the troop. Female mandrills lack these vivid facial markings. Their coloration is predominantly olive green with pale blue noses, allowing them to blend into the forest environment.
Birds
Many species of birds are known for their brilliant plumage. Tropical parrots like macaws and cockatoos boast a palette of reds, greens, blues and yellows. The feathers of male birds-of-paradise found in New Guinea display iridescent emerald, violet and gold in elaborate plumes used for mating rituals. Hummingbirds native to North and South America glitter with metallic emerald, ruby, sapphire and topaz hues. Again, sexual selection drives the evolution of these vibrant rainbow colors that help attract mates.
| Bird Species | Rainbow Coloration |
|---|---|
| Macaws | Reds, greens, blues, yellows |
| Cockatoos | Reds, greens, blues, yellows |
| Birds-of-paradise | Emerald, violet, gold |
| Hummingbirds | Emerald, ruby, sapphire, topaz |
Reptiles
While less common in reptiles, some species do display rainbow iridescence. The rainbow boa is a beautifully colored snake found in Central and South America. It earns its name from the multicolored sheen created by its iridescent scales in shades of purple, blue, green and orange. Chameleons are famous color changers. The panther chameleon from Madagascar can shift between a rainbow of colors depending on mood, temperature, communication and camouflage needs. Tropical agamid lizards like the double-crested basilisk exhibit vibrant breeding colors of red, orange and green to attract mates.
Fish
Underwater habitats host diverse rainbow-hued species. Tropical fish like bettas, gouramis, platies, and guppies shine with metallic scales sprinkled with iridescent glitter. The mandarinfish displays magnificent rainbow colors. Reef habitats support wildcard species like the harlequin tuskfish, pass the parcel clownfish, and the psychedelic frogfish. These fish use their kaleidoscopic colors for mating displays and communication. Camouflage is also aided by an ability to change color to match surroundings. Interestingly, the vibrant colors are produced by crystalline pigment cells under translucent skin, rather than colored pigments like melanin.
Insects
While less common, some insects do flash flashy rainbow hues. Male swallowtail butterflies feature iridescent blue coloring on their wings to attract mates. Other butterflies like the blue morpho have shimmering blue upperwings. Beetles also sometimes display spectral colors, like the rainbow scarab. The phenomenon is caused by structural color rather than pigments. Microscopic ridges and channels in transparent overlapping scales reflect light and produce the rainbow effect.
Mollusks
Color-changing abilities evolved in some cephalopods like squid, octopus and cuttlefish. Specialized skin cells called chromatophores allow them to flash patterns and colors for camouflage and communication. Iridescent blues, greens, pinks and purples ripple across their skin surfaces. The Caribbean reef squid, common cuttlefish, and flamboyant cuttlefish are especially vibrant species.
Conclusion
In summary, rainbow coloration is uncommon in the animal kingdom and found mainly in select species of birds, reptiles, fish, insects and mollusks. Primates like the mandrill acquire rainbow hues through sexual selection. In other animals, the colors variously serve purposes like attracting mates, camouflage, mimicry and communication. Structural properties of skin, scales and feathers produce the rainbow iridescence rather than pigments. So while most animals sport more mundane coloration for survival, rainbow animals add extraordinary beauty and diversity to nature. Their rarity makes them even more wondrous.