Have you ever noticed that some animals seem to have huge eyes compared to the size of their heads? Those big peepers aren’t just for looks – they serve an essential purpose. Let’s look at some animals known for their enormous eyes and find out why they evolved that way.
Tarsier
The tarsier is a small primate found in the forests of Southeast Asia. It has enormous eyes relative to its body size – each is about the same size as the animal’s entire brain! Tarsiers are nocturnal, and those giant eyes allow them to see well in the dark when hunting for insects and small vertebrates.
Their eyes are fixed in their sockets, so they must turn their head to follow their prey. Tarsiers also have excellent night vision from their large eyes.
Kinkajou
The kinkajou is a rainforest mammal found in Central and South America. With its big golden eyes covering much of its face, it almost looks like a stuffed animal! Kinkajous are arboreal, meaning they live in trees, and their massive eyes help them see at night.
Their eyes have a reflective layer called the tapetum lucidum that makes their eyes shine in the dark, like a cat’s.
Slow Loris
You can guess what adaptation the slow loris is known for based on its name alone! Found in the rainforests of Southeast Asia, the slow loris has the largest eyes of any primate relative to its body size.
Their eyes comprise about 10% of the slow lorises’ total weight. With those huge eyes, slow lorises have excellent night vision to spot insects and fruit in the dark rainforest. Plus, they make the loris look irresistibly cute.
Colugo
The colugo, also known as the Sunda flying lemur, is a mammal that glides between trees in the tropical forests of Southeast Asia. It’s easy to see why it’s called a “flying” lemur when you look at those enormous, bulging eyes!
The colugo has some of the most prominent eyes in proportion to the face of any mammal. These oversized peepers give it excellent vision and depth perception to navigate the forest canopy at night safely.
Bushbaby
Found throughout sub-Saharan Africa, bushbabies are pint-sized primates with diurnal and nocturnal species. They all share the trait of comically large eyes, which inspired their funny name!
Those expansive baby blues take up much of the bushbaby’s tiny head, allowing these primates to see clearly at night while hunting for insects and fruit. Bushbabies can focus quickly on small prey in low light with their baseball-sized eyes.
Red-eyed Tree Frog
This iconic cute rainforest frog from Central and South America owes its name to its bulging candy-apple red eyes. Compared to its body size, the red-eyed tree frog has some of the largest eyes in the animal kingdom!
These expansive eyes with horizontal pupils allow red-eyed tree frogs to see in almost any direction to spot food and danger in the rainforest. Their eyes also help these master leapers target their landing on branches.
Lemurs
Lemurs are primates found only on the island of Madagascar. Many lemur species have large, round eyes to help them see at night. The biggest eyes of all lemurs belong to the aye-aye. This bizarre-looking endangered lemur has eyes that are so big they stick out from the bony eye sockets in their skull!
Aye-ayes use their giant googley eyes and sensitive ears to find wood-boring insect larvae at night. Lemurs like the aye-aye and the nocturnal mouse lemur must have evolved large eyes to navigate and find food in Madagascar’s darkness.
Ostrich
Did you know that at 5 centimetres, the ostrich has the largest eyes of any land animal? This flightless bird wandering the savannas of Africa needs those massive peepers to be on the lookout for predators across wide open spaces. Their eyes are bigger than their entire brain!
Ostriches also have excellent vision from their giant eyes with pressure-sensitive retinas that detect movement from far away. With just a tiny head turn, an ostrich can scan a huge area for danger with those giant honkers.
Margay
The margay is a small wild cat found in Central and South American rainforest trees. Like many cats, the margay has large eyes to see well in low light for hunting at dawn, dusk and night.
But the margay’s eyes are exceptionally big at more than 25 millimetres wide, giving it the largest eyes relative to the body size of all cats! Their expansive peepers allow margays to judge distance when leaping between trees in pursuit of birds, monkeys and opossums.
Leaf-tailed Gecko
The leaf-tailed gecko lives in the rainforests of Madagascar and has some of the bulgiest eyes relative to its head size in the entire animal kingdom! These huge eyes help the gecko hide among leaves with its camouflaging body while still seeing predators and prey clearly.
Those colossal peepers also have many densely packed receptor cells to let geckos see colour and intricate patterns for hunting insects and spiders at night.
Ogre-faced Spider
Found in humid forests from Malaysia to Hawaii, the ogre-faced spider gets its name from—you guessed it—its monstrous eyes! Their enormous eyes are estimated to make up two-thirds of the surface area of their face.
Like other nocturnal hunters, these sizable eyes allow the spider to absorb more light at night to spot jumping insects from far away. As if this spider wasn’t terrifying enough already, now you know it also has massive bulging eyes like a monster!
Owls
Owls are known for their massive eyes, making up as much as 3% of an owl’s total body weight! Their extraordinarily large eyes are tube-shaped and immobile, so owls must turn their heads to see in different directions. While this limits an owl’s eye movement, it maximizes their binocular vision for depth perception when hunting.
Different owl species have varied eye sizes and colours based on their habitat and whether they hunt at night or day. From the deep black eyes of a great horned owl to the brilliant orange ones of a snowy owl, these raptors have some of the biggest and most stunning eyes in the animal kingdom. Just don’t be surprised if their giant glare leaves you feeling hypnotized!
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