The aye-aye (Daubentonia madagascariensis) is a lemur native to the island of Madagascar and the world's biggest nocturnal primate. They are solitary creatures and spend their days asleep in the branches and searching for food at night.
The most unusual feature of the aye-aye is its extremely narrow middle finger, which it uses to tap on trees to find grubs under the bark. The aye-aye listens for echoes to find hollow areas in the trees, a method called percussive foraging. Once an individual has found a hollow part of a tree, it gnaws into the bark and uses its middle finger to hunt for grubs and insects inside the tree.
The aye-aye's finger is a remarkably specific adaptation, allowing it to fill a small ecological niche and only compete with other aye-ayes for the grubs and insects in trees. Despite this specific adaptation to eating insects, the aye-aye can also be found eating seeds, fungi, and fruits, which makes it an omnivore. You can learn more about animal adaptations in this lesson.
Unfortunately, this unique primate is listed as "threatened" on the International Union for the Conservation of Nature's Red List. The aye-aye is considered unlucky and an omen of death by the local population, who often kill or poach aye-ayes when they see them. Challenging conservation situations like these call for multiple experts on science and human rights issues to come together to find a solution.
To lean more about endangered species, check out Endangered Species 1: Why Are Species Endangered? and Endangered Species 2: Working to Save Endangered Species.