Vision | Visual Adaptations to the Deep Sea

The deep ocean is not as dark as some imagine; the upper 1000. m contains dim residual sunlight and all depths are home to bioluminescent animals. Consequently, the majority of deep-sea fish have well-developed eyes that maximize sensitivity. Specializations for vision in the deep sea include: upwardly directed eyes whose limited visual field is often enhanced by downward-facing ocular diverticula, tiered rod-only retinae, large pupils, and tapeta. Furthermore, because the deep sea is spectrally restricted, most deep-sea fish possess only a single visual pigment absorbing at short wavelengths, although some stomiids are sensitive at longer wavelengths enabling them to perceive their own long-wave bioluminescence.