Whale coloration is complex, exhibiting a wide range of pigmentation tied to survival and species identification. There is no single color for all whales, but rather a spectrum of colors and patterns that have evolved as sophisticated adaptations to the ocean environment. Their coloration is a functional trait, varying from deep-sea camouflage to distinctive markings used for communication and hunting.
The Spectrum of Whale Coloration
Across the nearly 90 species of cetaceans, the dominant colors are shades of black, slate gray, blue-gray, and white. These colors are not uniform across the body but are typically distributed in patterns, often with the dorsal (top) surface being darker than the ventral (bottom) surface.
The largest animal on Earth, the Blue Whale, is not purely blue but has a mottled, grayish-blue skin that appears blue when submerged underwater. Many species, such as the Gray Whale, exhibit a dark, slate-gray coloration mottled with white patches. The pigmentation provides a background-matching effect, helping the animals blend into the vast ocean. This distribution of light and dark pigment is a foundational characteristic of whale appearance.
The Function of Countershading
The light-bottom, dark-top pattern is a biological defense mechanism known as countershading. When a whale is viewed from above by a predator or prey, its dark back blends with the dim, deep water below, essentially erasing the animal’s silhouette.
When the animal is viewed from beneath, its lighter underside is seen against the bright, sunlit surface waters. This lighter pigmentation helps the whale disappear against the illuminated water. Countershading is effective for smaller cetaceans to avoid being seen by predators or prey.
Distinctive Species Coloration
While many whales display the countershaded pattern, some species feature specific color markings that serve additional purposes. The Orca, or Killer Whale, is recognizable by its stark black-and-white pattern, a form of disruptive coloration. The black back and white chest, along with the distinct white eye patches and saddle patch behind the dorsal fin, break up the animal’s body outline.
Humpback Whales have dark gray to black bodies, but they possess large patches of white on the underside of their flukes (tail) and pectoral fins. The unique pattern of white on the fluke is like a fingerprint, allowing researchers to identify individual whales. The white undersides of the pectoral fins may also be used in hunting, possibly reflecting light to disorient or startle schools of fish.
Environmental and Age-Related Changes
A whale’s color can also be temporarily altered by external factors, leading to appearances not related to its genetic pigmentation. Blue Whales were nicknamed “sulphur bottom” whales because their pale undersides sometimes take on a yellowish-green tint. This discoloration is caused by accumulation of microscopic algae called diatoms that attach to the skin in colder feeding waters.
Age also influences coloration, as Beluga Whales are born a dark gray color. As they mature, these whales gradually lighten, becoming completely white between the ages of five and twelve. Additionally, the pale scars left by battles or from parasites like barnacles can further enhance the mottled appearance of a whale’s skin.