When we think of the color blue, animals like blue whales, bluebirds, and bluefish often come to mind. However, blue coloration is relatively rare in the animal kingdom. Most blue animals get their color not from pigmentation, but through the physical structure of their feathers, scales, or hair. Finding truly blue-colored animals takes a bit of searching.
Blue in Nature
Blue is an unusual color in nature. It is not found often as skin pigmentation in animals. The blue color is caused by the structure of the animal’s feathers, scales, or hair reflecting the shorter blue wavelengths of light.
Structural colors happen when microscopic structures in animals’ skins or feathers cause interference of light waves, reflecting only certain colors back. Unlike pigment colors that absorb certain wavelengths of light, structural colors specifically reflect just one wavelength. They appear iridescent and can look different from different viewing angles.
Bluebirds
One of the most commonly known blue birds is the Eastern Bluebird. The males are a brilliant royal blue on the back and head, with a red or chestnut breast. The blue color comes from the structure of the feathers, not from pigment. The feathers have a spongy layer underneath the outside barbs that reflects the blue wavelength.
Eastern Bluebirds live in open country across Eastern North America. They nest in cavities in trees or birdhouses. These birds mostly eat insects and berries. They are a welcome sign of spring to many when they return from their southern wintering grounds.
There are several other species of bluebirds worldwide, such as:
Western Bluebird
Found along the Pacific coast, males are bright blue above and rusty colored below. They were threatened by competition with non-native starlings and loss of habitat, but are recovering well with nest box programs.
Mountain Bluebird
A thin, long-tailed relative of other bluebirds that lives in more open terrain in western North America. Males are bright blue with a pale belly.
Sialia sialis (Eurasian Bluebird)
Closely related to the Eastern Bluebird, this species lives across Europe and into temperate Asia. Males are bright blue on the head, back, and tail.
| Species | Location |
|---|---|
| Eastern Bluebird | Eastern North America |
| Western Bluebird | Western North America |
| Mountain Bluebird | Western North America |
| Eurasian Bluebird | Europe to Asia |
Blue Jays
Blue jays are a common backyard bird in the eastern and central U.S. and Canada. They are known for their bright blue feathers and loud, scolding calls. The blue color comes from light refracting through the molecular structure of the feathers. The exact mechanism behind structural blue involves the scattering of light off arranged melanin granules within the feathers.
Blue Jays eat a wide variety of foods, like nuts, seeds, fruits, insects, frogs, eggs, and even small birds. They sometimes rob nests and caches of other birds like robins and sparrows. Intelligent and curious, blue jays are bold birds that can become quiet when stealthily approaching a feeder.
Blue Penguins
Penguins are aquatic flightless birds most often associated with Antarctica. However, some smaller penguin species live in warmer climates, including Australia and New Zealand. The Little Penguin of southern Australia and New Zealand is also called the Fairy or Blue Penguin for the bluish tint to its dark plumage.
The blue color is structural, caused by the arrangement of melanin grains in the penguin’s feathers. It appears bluer in the Penguin’s face, chin, and upperparts. The blue tint may also help camouflage the penguin in the water when viewed from below.
Blue Penguins are the smallest penguin species, only about 10-12 inches tall. They nest along the coast in burrows or small caves. Penguin pairs often return to the same nest site each year. The Little Penguin is listed as a protected species but faces threats from habitat loss, climate change, pollution, and predators.
Blue Whales
The largest animal on earth, the blue whale, also sports a blue-gray coloration. However, their color is not structural but comes from pigmentation in their skin. The pigment is believed to be a blue-gray lipochrome.
Blue whales have long, streamlined bodies that can reach lengths over 100 feet and weights of 150 tons or more. Their mottled color pattern helps camouflage these giant whales in the ocean. Blues whales live globally and often feed on tiny shrimp-like krill.
Their population was devastated by commercial whaling in the 1900s when over 350,000 were killed. Blue whales have been protected since 1966 but only number around 10,000-25,000 individuals today. Ship strikes, climate change, pollution, and noise pollution continue to threaten these magnificent endangered whales.
Other Blue Animals
Beyond birds and whales, several other animals also display blue hues:
Blue-ringed Octopus
A small but highly venomous octopus species found in tide pools and coral reefs of the Pacific and Indian Oceans. They display bright blue rings when threatened. Their venom contains tetrodotoxin, which can be fatal to humans.
Blue Morpho Butterfly
A vivid blue tropical butterfly common in Central and South America. Their wings reflect blue light due to the microscopic structure of the scales.
Blue Dragon Sea Slug
A small marine sea slug or nudibranch with blue and black striped coloring. They live on the ocean floor off the coast of southern Australia.
Blue Poison Dart Frog
A brightly colored poisonous frog native to the tropical rainforests of Suriname. It secretes a mild toxin to deter predators.
| Animal | Habitat |
|---|---|
| Blue-ringed Octopus | Pacific and Indian Oceans |
| Blue Morpho Butterfly | Central and South America |
| Blue Dragon Sea Slug | Southern Australia |
| Blue Poison Dart Frog | Suriname Rainforests |
Conclusion
While blue coloration is relatively uncommon in the animal kingdom, some birds, insects, marine life, and a few mammals exhibit shades of blue. Vivid blues often come from the microscopic structure of feathers, scales or shells rather than pigments. Blue whales are one exception, showing their blue-gray hue from skin pigmentation. Blue animals fascinate us with their beautiful iridescent colors. Learning how rare or unusual these creatures are highlights the importance of protecting them and their fragile habitats.
