5 unique animals that change eye colours

Nature never ceases to amaze with its clever adaptations, and eye colour changes in animals stand out as one of the coolest tricks up its sleeve. While human eye colour stays pretty much the same, certain creatures tweak theirs based on seasons, mood, age, or environment to survive better. This isn't magic; it's biology at work, helping with camouflage, hunting, or spotting food in tough conditions. From Arctic wanderers to ocean shapeshifters, these changes show how eyes evolve as survival tools.


Here are 5 unique animals that change the colour of their eyes

Reindeer are the only known mammals with seasonally changing eye colour. Their tapetum lucidum shifts from gold in summer, reflecting most light directly to deep blue in winter, increasing retinal sensitivity by up to 1,000 times for UV/blue light detection under Arctic twilight and snow. This adaptation aids foraging and predator spotting, confirmed by multiple studies from UCL and others.

Common loons have visible red eyes during the summer breeding season. This happens because of their retinal pigments, which help in underwater vision and attracting mates. In winter, their eyes dull to brown-gray. Young loons start with paler eyes that intensify with maturity. This seasonal shift matches plumage changes and migration, though exact reasons remain debated among expertsPhoto: Wikimedia Commons

Octopuses change eye colour along with skin using chromatophores. Eyes darken/lighten for camouflage, matching backgrounds perfectly. This quick shift in milliseconds aids hunting and escape in reefs.

Cuttlefish dynamically alter skin and eye colour and patterns via chromatophores for camouflage. Their W-shaped pupils and polarisation-sensitive eyes enhance hunting in murky water. Eye shade matches the surroundings rapidly.

Catsharks, like the small-spotted variety, adjust their iris color from black to bright blue or green in low-light conditions. This rapid change, triggered by dim environments, enhances their vision by optimizing light entry through pupil dilation and pigment shifts in the iris. It helps these nocturnal sharks hunt effectively in deep, murky waters. This ability lets them see better when it’s dark, making it easier to find prey. By changing eye color quickly, catsharks adapt to their surroundings, staying alert and ready to catch food even in challenging lighting. This skill gives them an advantage underwater at night.