Gorillas cannot see well in darkness because they are diurnal primates. Like humans, gorillas have a visual system highly specialized for daytime activity and bright light conditions. They are active from dawn until dusk, and their biology reflects an evolutionary trade-off that prioritizes color and detail over low-light sensitivity.
Gorillas’ Daytime Vision
Gorillas possess a highly developed visual system that allows them to navigate and forage effectively in their shaded, complex habitats. They see the world in full color because their retinas contain three types of cone cells, granting them trichromatic vision, much like humans. This ability to distinguish between red, green, and blue wavelengths is useful for identifying ripe fruits and tender leaves against the forest’s green canopy. Their forward-facing eyes provide excellent binocular vision, enabling them to perceive depth and accurately judge distances, while a fovea ensures high visual acuity and sharp focus.
The Science of Night Vision
The ability to see in low-light conditions depends on specific biological features that gorillas largely lack. The retina contains two main types of photoreceptor cells: cones, responsible for color and sharp vision in bright light, and rods, which function best in dim light. Gorillas, being diurnal, have a high concentration of cones relative to rods in their retinas, unlike nocturnal animals which have a higher rod ratio to capture scarce light. Furthermore, many animals with superior night vision have a tapetum lucidum, a reflective layer situated behind the retina. This layer bounces incoming light back through the photoreceptors a second time, increasing signal absorption. Gorillas and other great apes lack this structure.
Behavioral Confirmation
The daily behavior of gorilla groups strongly confirms their reliance on adequate daylight. Gorillas are strictly diurnal, consistently waking shortly after sunrise and compressing their entire daily cycle—foraging, traveling, and socializing—into the hours of sunlight. Every individual gorilla must construct a new nest before the light fades completely, usually starting this task in the late afternoon to settle into their sleeping platform by dusk. This necessity of settling into a secure nest before darkness descends is a direct behavioral consequence of their poor night vision, as they cannot safely navigate or detect predators once the environment is shrouded in darkness.