Tarsiers have eyes bigger than their brain
Despite measuring only 12 centimetres
(4.7 inches) long, a tarsier’s eyes are the same size as those of an orangutan. This is an adaptation to a nocturnal lifestyle of leaping from tree to tree in search of insect prey. The tarsier’s long-range vision helps it detect insects, small birds or even snakes through the dense Asian jungle. The rear of the eyes have pronounced indentations called foveae, in which rods and cones are packed very densely. This pit is a mechanism for producing a stable eyeline like a high-powered telescope.
Tarsiers are thought to be fairly primitive primates and may use similar survival tactics as some of the very first mammals that lived just after the demise of the dinosaurs. These animals came out at night to avoid predators, and their surviving descendants continue to do the same. Tarsier fossils from 50 million years ago have been discovered to be almost identical to their modern-day counterparts.