Aye-aye (Daubentonia madagascariensis) Fact Sheet: Physical Characteristics

Body measurements from Feistner and Sterling 1995; Mittermeier et al. 2010; Schwitzer et al. 2013.

Body Shape (from Schwitzer et al. 2013 unless otherwise noted)

• Medium-sized lemur
  • Largest of the fully nocturnal prosimians (lemurs, galagos, and lorises)
  • Body slender, bulky appearance due to thick hair
• Limbs
  
  • Short and slender
  • Hindlimbs longer than forelimbs
• Forefeet large, relative to body size
  • 5 digits
    • 3rd and 4th fingers elongate (Owen 1863)
    • 3rd extremely thin; skeletal in appearance (Mittermeier et al. 2010)
  • Nails on all fingers except the first, which has a flattened nail
    • "Claw-like"
  • "Thumb" flexible, but not truly opposable to other digits
• Hindfeet
  • 5 digits, less disparate in length than those of the forefeet
  • Claws on all toes except the first, which has a flattened nail
  • "Big toe" nearly opposable to other digits
• Tail
• Long and bushy
• Longer than the head and body

Facial Characteristics (from Mittermeier et al. 2010; Schwitzer et al. 2013 unless otherwise noted)

• Face squirrel-like
• Face and muzzle short
• Brow high
• Eyes facing forward
• Ears
  
  • Large, black, and oval-shaped
  • Naked; lack hair (Quinn and Wilson 2004)
  • Protrude laterally
  • Highly mobile, possibly used to locate hollows in decayed wood
• Eyes prominent
  • Yellow-orange or sandy-brown; surrounded by dark rings (Quinn and Wilson 2004)
  • Nictitating membranes, transparent 3rd eyelids, present (Quinn and Wilson 2004)
    • Moistens and cleans the eye
• Nose
• Pinkish in color (Quinn and Wilson 2004)
• Teeth
  
  • Reduced in number (Owen 1863; Schwitzer et al. 2013)
  • 18 in total; a typical lemur has a compliment of 30-36 (Owen 1863; Schwitzer et al. 2013)
  • Incisors large and curved; chisel-like
    • Grow continually throughout life; wear down with use
      • Uncommon in primates
    • Enamel on front surface only
  • Diastema large; gap between the incisor and molars of the lower jaw bones
• Click here to view 3-D model of an aye-aye cranium or jaw

Adult Pelage/Coat (from Schwitzer et al. 2013 unless otherwise noted)

• Body covered in dark brown or black hair
  • Hairs tipped in white
  • Brindled appearance (Mittermeier et al. 2010)
  • Guard hairs long and coarse
• Chest, throat, and facial hairs paler than those of the body
• Tail monochromatic in color (Mittermeier et al. 2010)
• Solid brown or black (Mittermeier et al. 2010)

Sexes alike (Feistner and Sterling 1995)

Male features (from Schwitzer et al. 2013)

• Genital characteristics
• Scrotum naked
• Baculum/penis bone present

Female features

• Single pair of mammary glands (from Schwitzer et al. 2013)
• Located near the groin, not on the chest

Nocturnal adaptations

• Large eyes, specialized for visual acuity in low light (Andriamasimanana 1994)
  • Reflective tapetum lucidum; specialized reflective cells help deflect light toward the retina
  • Possible blue color vision (from Melin et al. 2012)
    • Functional opsin genes, suggest sensitivity to blue wavelength light, though experts disagree
    • 2 proposed explanatory hypotheses: (1) assists with location of blue flowers of the traveler's tree (Ravenala madagascariensis) and (2) enables detection of (urine) scent marks in twilight

Foraging adaptations

• Specialized fingers
  • Elongate 3rd digit with ball and socket joint (metacarpal) used to search and probe for food (Erickson 1995a; Milliken et al. 1991)
    • Tap finger on bark to locate subsurface cavities, often created by insect larvae; see description of percussive foraging under the Diet & Feeding tab (Erickson 1995a)
    • Used to dig out seeds and insect larvae (Sterling and McCreless 2006)
      • Finger is highly flexible; capable of 360^o movement and operates independently of other digits (Erickson 1994; Milliken et al. 1991)
      • Able to fold (nearly flat) under or over the hand; enhances probing
    • Dipped into flowers to secure nectar (Sterling and McCreless 2006)
• Large ears assist with echolocation
  • Help the animal identify subsurface cavities
• Incisors grow continually
  • Mitigates against wear caused when the animal chews through wood and hard seeds (Erickson 1994; Schwitzer et al. 2013)
    • Pry bark from trees to gain access to subsurface insects (Sterling and McCreless 2006)
    • Scrape fungus and cankers (Sterling and McCreless 2006)
    • Gouge into seeds (Sterling and McCreless 2006)

Chromosome number

• Diploid number
• 2n = 30 (Tattersall 1982)

Fecal characteristics

• Feces resembles that of a rabbit (from Bartlett 1862)
• Composed of separate, small, nearly round balls

Specialized fingers on the aye-aye's forefeet are used to forage for and secure food. This slender, elongate third digit is tapped against tree bark in percussive foraging. Aye-ayes listen to the echoed sound to identify the location of subsurface grubs. The finger is then used to fish out the meal through a small, chewed hole.

Image credit: © Rama from Wikimedia Commons. Some rights reserved.

Andriamasimanana (1994)
Bartlett (1862)
Erickson (1994)
Erickson (1995a)
Feistner and Sterling (1995)
Melin et al. (2012)
Milliken et al. (1991)
Owen (1863)
Schwitzer et al. (2013)
Sterling and McCreless (2006)
Tattersall (1982)