The color of octopuses has long fascinated scientists and observers alike. Octopuses can rapidly change color and texture to camouflage themselves from predators and prey. But what is their true, underlying color underneath all those chromatophores? The answer is complex and sheds light on the amazing biology of these cephalopods.
Octopus Chromatophores
An octopus’s ability to change color starts with specialized pigment cells in their skin called chromatophores. These are little sacs filled with pigments of red, orange, yellow, brown, and black. When an octopus receives a neural signal, muscles around the chromatophores contract, expanding the colored sacs and revealing the pigment. An octopus has up to three million chromatophores, allowing it to create complex moving displays of color and texture across its soft body. This helps the octopus camouflage almost instantaneously into its surroundings.
True Skin Colors
So what color is an octopus underneath all those chromatophores? Researchers have found that without their pigment sacs expanded, most octopus species share a similar drab tone. The octopus’s skin is effectively colorless or a light beige/yellow. The white patches or ‘false eyespots’ that appear on some octopuses are also devoid of chromatophores. So while octopuses have the amazing ability to dynamically change color, their baseline true color is relatively muted. This makes biological sense, as having bright or dark true skin colors would defeat their camouflage capabilities.
Exceptions
However, there are a few exceptions where octopuses naturally show more vibrant colors without actively expanding their chromatophores. For example:
– The Mimic Octopus has black and white zebra-like bands over much of its body. This provides a baseline camouflage resembling a venomous sea snake.
– The Wonderpus octopus has distinct burgundy and white contrasting stripes over its soft body.
– The Atlantic Pygmy octopus is a vivid red hue, marked by bright white spots.
– Some deep sea octopuses like Vulcanoctopus hydrothermalis have naturally bright red skin, which is theorized to camouflage them in the dark hydrothermal vent environments where they live.
So while most shallow water octopus species share a common beige/yellow base skin tone, exceptions do exist. Evolution has driven some unique baseline colorations.
Color and Genetics
An octopus’s color is driven largely by the pigments contained in its chromatophores and iridophores (iridocytes), which contribute to iridescent blues and greens. Their genetic makeup determines these specialized cells and pigments. However, octopus color can also be affected by diet, water temperature, and light exposure during development. This indicates both genetic and environmental factors play a role. Fascinatingly, some color traits in octopus appear linked to specific genes. For example, the Atlantic Pygmy octopus’s vivid red hue is controlled by a specific gene variant. When cross-bred with normal brown octopuses, the red color persists in offspring as a dominant trait. Such research is shedding light on the genetic basis of adaptive octopus coloration.
Color and Health
An octopus’s appearance can also change temporarily based on its health and mood. Stressed or sick octopuses often appear pale and unable to produce bright, dynamic displays. This is likely due to physiological constraints that restrict their color-changing abilities. In some species like Octopus chierchiae, brooding mothers tend to become pale and muted as they stop actively foraging during the final weeks of protecting their eggs. So an octopus’s color is not always an exact representation of its steady state. Context matters.
Color and Communication
Beyond camouflage, octopuses can also use color for communication. Chromatic flashing displays are used to ward off competitors, attract mates, startle prey, and confuse predators. Different color patterns and textures convey different signals. For example, the Caribbean Reef Octopus flashes white when alarmed, but red when angered. The capabilities and uses of an octopus’s color signals are still being studied. Their chromatic language reflects complex behaviors.
Conclusion
The question “what color is an octopus?” turns out to not have one simple answer. Most octopus species share a muted yellowish tone in their natural state. But special pigment cells called chromatophores allow them to dynamically flash colors for camouflage and communication. Some species have striking natural color patterns that differ from the norm. Diet, genetics, health and other factors further influence an octopus’s appearance. So while we cannot pinpoint one true color, studying octopus chromatophores reveals amazing biology and continually surprises scientists. The natural world contains such intricate splendor in even a simple question about color.
