The tiny primate with eyes bigger than its brain
This tiny primate has eyes bigger than its brain — and can turn its head almost all the way around.
Which one is REALLY true about the Tarsier?
The short version
The tarsier's eyeballs are each about as big as its whole brain and can't move in their sockets, so it rotates its head nearly 180 degrees like an owl. It's the only fully carnivorous primate, and it communicates in ultrasound too high for most predators to hear.
Why it's so weird
- ✓The Tarsier can rotate its head almost a full half-circle in each direction, just like an owl.
- ✓The Tarsier has eyeballs so huge that each one is about as big as its entire brain.
- ✓The Tarsier has eyes fixed in their sockets that cannot move at all, which is why it spins its head instead.
- ✓The Tarsier is the only primate that eats no plants whatsoever, leaping through the dark to snatch insects, lizards, and small birds.
- ✓The Tarsier screams to others of its kind in ultrasound, at pitches too high for most to hear.
You could line up about 8 of them along a 7-year-old!
The full story
This tiny primate has eyeballs that are literally bigger than its own brain. Meet the tarsier, a pocket-sized hunter that lives in the forests of Southeast Asia. Each of its enormous eyes is about as big as its entire brain, and they are so huge that they cannot move in their sockets at all. To make up for it, the tarsier can rotate its head almost a full half-circle in each direction, just like an owl, to look directly behind itself. It is also a pure carnivore, the only primate that eats no plants whatsoever, leaping through the dark to snatch insects, lizards, and even small birds right out of the air. And it talks in secret. Tarsiers scream to each other in ultrasound, at frequencies so high that most of their predators simply cannot hear them coming. Follow for more weird animal facts.
A tarsier's eyeballs are so gigantic that each one fills its eye socket completely, leaving no room for the tiny muscles that would normally swivel an eye around. So instead of moving its eyes, the tarsier moves its whole head, using a super-bendy neck to swing it almost halfway around in each direction, just like an owl. The eyes grew this huge because tarsiers hunt in the dark and, unlike many night animals, their eyes have no mirror-like layer to bounce light around, so they have to be enormous to soak up every bit of dim light.
📚 Source: Tarsier - Wikipedia ↗Scientists led by Marissa Ramsier (Humboldt State University) recorded wild Philippine tarsiers using special bat-detector microphones and caught them making calls around 70 kHz, far too high for humans or most predators to hear. They also tested the tarsiers' ears and found their hearing reaches about 91 kHz (Ramsier et al., 2012, Biology Letters).
📚 Source: Primate communication in the pure ultrasound (Ramsier et al., 2012, Biology Letters) ↗Watch the 45-second version
Tarsier gallery
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“The Tarsier can rotate its head almost a full half-circle in each direction, just like an owl.”
“The Tarsier drinks water through its skin without ever using its mouth.”
“The Tarsier has eyeballs so huge that each one is about as big as its entire brain.”