Aye-Aye – Daubentonia Madagascariensis
It is the world’s largest nocturnal primate, and is characterized by its unusual method of finding food; it taps on trees to find grubs, then gnaws holes in the wood using its forward slanting incisors to create a small hole in which it inserts its narrow middle finger to pull the grubs out. This foraging method is called percussive foraging. The only other animal species known to find food in this way is the striped possum. From an ecological point of view the aye-aye fills the niche of a woodpecker, as it is capable of penetrating wood to extract the invertebrates within.
The aye-aye is the only extant member of the genus Daubentonia and family Daubentoniidae. It is currently classified as Endangered by the IUCN; and a second species, Daubentonia robusta, appears to have become extinct at some point within the last 1000 years.
The genera, Daubentonia, was named after the French naturalist Louis-Jean-Marie Daubenton by his student, Étienne Geoffroy Saint-Hilaire, in 1795. Initially Geoffroy considering using the Greek name, Scolecophagus (“worm-eater”) in reference to its eating habits, but he decided against it because he was uncertain about the aye-aye’s habits and whether other related species might eventually be discovered. In 1863, British zoologist John Edward Gray coined the family name Daubentoniidae.
The French naturalist, Pierre Sonnerat was the first to use the vernacular name, “aye-aye”, in 1782 when he described and illustrated the lemur, though it was also called the “long-fingered lemur” by English zoologist George Shaw in 1800—a name that did not stick. According to Sonnerat, the name “aye-aye” was a “cri d’exclamation & d’étonnement” (cry of exclamation and astonishment). However, American paleoanthropologist Ian Tattersall noted in 1982 that the name resembles the Malagasy name “hai hai” or “hay hay”, which is used around the island. According to Dunkel et al. in 2012, the widespread use of the Malagasy name indicates that the name could not have come from Sonnerat. Another hypothesis proposed by Simons and Meyers in 2001 is that it derives from “heh heh“, which is Malagasy for “I don’t know”. If correct, then the name might have originated from Malagasy people saying “heh heh” to avoid saying the name of a feared, magical animal.
Evolutionary history and taxonomy
Due to its derived morphological features, the classification of the aye-aye has been debated since its discovery. The possession of continually growing incisors (front teeth) parallels those of rodents, leading early naturalists to mistakenly classify the aye-aye within the mammalian order Rodentia and as a squirrel, due to its toes, hair coloring, and tail. However, the aye-aye is also similar to felines in its head shape, eyes, ears and nostrils.
The aye-aye’s classification with the order Primates has been just as uncertain. It has been considered a highly derived member of the family Indridae, a basal branch of the strepsirrhine suborder, and of indeterminate relation to all living primates. In 1931, Anthony and Coupin classified the aye-aye under infraorder Chiromyiformes, a sister group to the other strepsirrhines. Colin Groves upheld this classification in 2005 because he was not entirely convinced the aye-aye formed a clade with the rest of the Malagasy lemurs, despite molecular tests that had shown Daubentoniidae was basal to all Lemuriformes, deriving from the same lemur ancestor that raftedto Madagascar during the Paleocene or Eocene. In 2008, Russell Mittermeier, Colin Groves, and others ignored addressing higher-level taxonomy by defining lemurs as monophyletic and containing five living families, including Daubentoniidae. 
Further evidence indicating that the aye-aye belongs in the superfamily Lemuroidea can be inferred from the presence of a petrosal bullae encasing the ossicles of the ear. However, interestingly, the bones themselves may have some resemblance to those of rodents. The aye-ayes are also similar to lemurs in their shorter back legs.
Anatomy and morphology
Young aye-ayes typically are silver colored on their front and have a stripe down their back. However, as the aye-ayes begin to reach maturity, their bodies will be completely covered in thick fur and are typically not one solid color. On the head and back, the ends of the hair are typically tipped with white while the rest of the body will ordinarily be a yellow and/or brown color.
In length, a full-grown aye-aye is typically about three feet long with a tail as long as its body. Among the aye-aye’s signature traits are its fingers. The third finger, which is thinner than the others, is used for tapping and grooming, while the fourth finger, the longest, is used for pulling bugs out of trees.
The complex geometry of ridges on the inner surface of aye-aye ears helps to sharply focus not only echolocation signals from the tapping of its finger, but also to passively listen for any other sound produced by the prey. These ridges can be regarded as the acoustic equivalent of a Fresnel lens, and may be seen in a large variety of unrelated animals, such as lesser galago, bat-eared fox, mouse lemur, and others.
Females have two nipples located in the region of the groin.
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