The Giant Squid, Architeuthis dux, represents one of the ocean’s most elusive creatures, residing in the perpetual darkness of the deep sea. Its habitat, located hundreds of meters below the surface, has historically made it nearly impossible to study in its natural state. For centuries, knowledge of the animal was limited to dead specimens that washed ashore or were recovered from the stomachs of sperm whales. This lack of direct observation meant that determining the squid’s true appearance, especially its coloration, remained a long-standing biological mystery until modern deep-sea technology allowed for rare, verified sightings.
Determining the Live Color
The few instances of verified footage of a living giant squid in its natural deep-sea habitat have provided a definitive answer to its color. The initial successful filming in 2012 revealed a coloration that surprised researchers. Rather than the dark red or black traditionally assumed for deep-sea animals, the living specimen appeared to be a silvery-metallic and gold hue. This observation contrasted sharply with most deep-sea cephalopods, which are typically a uniform red color.
The main body, or mantle, and the arms displayed a reflective, metallic sheen when illuminated by the submersible’s lights. This silvery appearance is likely due to layers of specialized light-reflecting cells below the skin’s surface. However, other rare sightings and a specimen brought to the surface displayed a more uniform reddish-brown coloration. The consensus now suggests the squid possesses a base color of rich reddish-brown or reddish-orange, overlaid with a highly reflective, metallic layer that only becomes apparent under artificial illumination.
Pigmentation and Camouflage
The coloration observed in the giant squid is rooted in a fixed biological mechanism that serves as passive camouflage in the aphotic zone. The reddish-brown hue comes from dense, fixed pigments known as ommochromes, which are commonly found in cephalopods. These pigments absorb blue and green light wavelengths. Since red light is filtered out by seawater within the first few hundred meters, a red object at depth reflects no color and appears completely black, making the squid virtually invisible.
Unlike many shallow-water cephalopods, the giant squid does not rely on dynamic color changes for communication or active camouflage. While it possesses chromatophores—pigment sacs controlled by muscle fibers—these cells are not used for the rapid, complex skin patterning seen in cuttlefish or octopus. The sheer lack of ambient light in the deep-water home means that complex visual signaling is unnecessary. This fixed, uniform coloration is an adaptation to low-light conditions. It is also likely due to the fact that its primary predator, the sperm whale, hunts using echolocation rather than sight.
How Observation Affects Color
The color of a giant squid is highly dependent on the circumstances of its observation, which explains the conflicting historical reports. The reddish-brown pigment begins to break down rapidly once the animal dies, a process known as post-mortem degradation. Specimens found washed ashore or recovered from the deep sea are frequently pale, having faded to white, pink, or gray due to the fast decomposition of the delicate pigment cells.
The way light interacts with the squid’s skin profoundly affects its perceived color. When researchers shine an artificial white light source, the red pigments are fully illuminated and become visible. This application of full-spectrum light is what allowed the metallic, silvery layer to be seen in the live footage, contrasting sharply with the duller appearance of dead specimens.