There is no known shark species that is predominantly red in coloration. While popular culture might sometimes depict fantastical creatures, the actual colors of sharks are rooted in biological and environmental factors. This absence of red is a fascinating aspect of their biology, directly tied to the physics of light in aquatic environments and the evolutionary pressures of marine life.
The True Colors of Sharks
Sharks typically exhibit a range of colors, including various shades of grey, blue, brown, and white. A very common coloration pattern among many shark species is countershading, a form of camouflage where the shark’s upper (dorsal) side is darker than its lower (ventral) side. When viewed from above, the dark back of the shark merges with the deep, dim ocean depths. Conversely, when seen from below, their lighter belly disappears against the brighter surface waters.
Many oceanic sharks, such as the great white shark, blue shark, and bull shark, exemplify this countershading with their neutral grey or blue-grey backs and white or creamy undersides. Blue sharks, for instance, are particularly known for their distinctive blue hue on their upper bodies and silver-white sides.
For sharks that inhabit the seafloor, like wobbegongs or nurse sharks, their coloration tends to be mottled browns or tans, blending with the seabed. Tiger sharks, found in shallower waters, possess vertical bars that resemble the flickering shafts of sunlight on the water’s surface, for effective camouflage. These diverse color patterns are all strategic adaptations for survival, enabling sharks to ambush prey and evade potential threats within their specific habitats.
Why Sharks Aren’t Red
Sharks are not red primarily due to the way light behaves in water and the evolutionary need for effective camouflage. Water strongly absorbs longer wavelengths of light, such as red, orange, and yellow, much more quickly than shorter wavelengths like blue and green. Red light penetrates only a few meters into the ocean, meaning that beyond shallow depths, red objects appear dark grey or black. Therefore, red coloration would offer little to no camouflage advantage for a shark in most marine environments.
The visual system of sharks also plays a role in their coloration. Research suggests that many shark species have monochromatic vision, meaning they perceive the world largely in shades of grey. They typically lack the cone cells necessary to detect red light. Since red light would not be discernible to them or their prey in most aquatic settings, developing red pigmentation would be biologically inefficient.
Shark skin pigmentation is largely composed of melanin, which produces black, grey, and brown hues, and structural colors from guanine crystals that create blue and silvery appearances. These naturally occurring pigments and structures are optimized for the blues and greens that dominate the underwater light spectrum. The absence of red in sharks is thus a testament to the powerful influence of their marine environment on their biological adaptations.