Cuttlefish adopt disruptive camouflage under dynamic lighting

Many animals avoid detection or recognition using camouflage tailored to visual features of their environment. The appearance of those features, however, can be affected by fluctuations in local lighting conditions, making them appear different over time. Despite dynamic lighting being common in many terrestrial and aquatic environments, it is unknown whether dynamic lighting influences the camouflage patterns that animals adopt. Here we test whether a common form of underwater dynamic lighting, consisting of moving light bands that can create local fluctuations in the intensity of light ('water caustics’), affects the camouflage of cuttlefish (Sepia officinalis). Owing to specialised pigment cells (chromatophores) in the skin, these cephalopod molluscs can dynamically adjust their body patterns in response to features of their visual scene. While cuttlefish resting on plain or patterned backgrounds usually expressed uniform or disruptive body patterns respectively, exposure to these backgrounds in dynamic lighting induced stronger disruptive patterns regardless of the background type. Dynamic lighting increased the maximum contrast levels within scenes, and these maximum contrast levels were associated with the degree of cuttlefish disruptive camouflage. This adoption of disruptive camouflage in dynamically lit scenes may be adaptive, reducing the likelihood of detection, or alternatively could represent a constraint on visual processing.