Wombats (Vombatus and Lasiorhinus spp.) Fact Sheet: Physical Characteristics

Body measurements

**Note: Tasmanian and Flinders Island subspecies slightly smaller.

• Skin and pelage (Moeller 1990)
  • Common wombat
    • Hair long, thick, coarse
    • Yellow-gray, sandy, to black; a few individuals cream-colored
  • Northern hairy-nosed wombat
    • Hair short, silky
    • Brown-gray, brown streaked with gray, brown, or black
  • Southern hairy-nosed wombat
    • Hair short, silky
    • Silver-gray or mottled brown-gray
    • Neck and chest often white
  • Skin strong, resistant to injury
    • Extremely tough over posterior third of back - "hard as a board" (Moeller 1990)
• Body and limbs (Horsup & Johnson 2008; McIlroy 2008; Moeller 1990; Taggart & Temple-Smith 2008)
  • Body - stocky, powerful, adapted to digging
    • Short, stout limbs and short neck
    • Massive, broad skull, flattened dorsoventrally (top to bottom)
    • Large, broad sacrum (pelvic bone)
  • Back - slopes down to vestigial tail (usually hidden in fur)
  • Forelegs- muscular
    • Feet with 5 forward-facing toes
    • Strong, flattened claws for digging
  • Hind legs- weaker, rotated inward (pigeon-toed)
    • Feet narrow, first toe long and nailless, points inward (similar to koalas and phalangers)
    • 2nd and 3rd toes joined by skin (syndactyly) (similar to phalangers, jumping marsupials, bandicoots)
  • Feet - rough, granular soles with thick pads
• Head (Horsup & Johnson 2008; McIlroy 2008; Moeller 1990; Taggart & Temple-Smith 2008, Hume 1999)
  • Shape
    • Common wombat - broad forehead tapering to rounded muzzle
    • Hairy-nosed wombats - wide, flat forehead with large, square muzzle
  • Eyes - small
  • Ears - small/rounded in common wombat, longer/pointed in hairy-nosed wombats
  • Nose - rhinarium (nose pad) is bare in common wombat, covered with fine hairs in hairy-nosed wombats
  • Mouth
    • Split upper lip allows grazing close to ground (Hume 1999)
    • Rodent-like teeth- specialized for grazing diet (Wells 1987; Murray 1998)
      • 1 pair incisors, no canine teeth, large diastema (gap), 1 pair premolars, 4 pairs molars
        • Only marsupial that has only 1 pair upper incisors
      • Teeth are rootless and grow continuously
        • Only marsupial that has continuously growing teeth
      • Molars tall with specialized surfaces for shearing and grinding plant material under high compressive forces
        • Opposing blades formed by high enamel ridges on tongue side of upper teeth, cheek side of lower teeth

• No major differences between the sexes (Triggs 1996)

• Adaptations to grazing diet (Murray 1998)
  • Continual tooth growth allows exploitation of wider variety of abundant but coarse and abrasive foods (leaves, stems, rhizomes, bark, etc.) - counteracts rapid wear
  • Specialized teeth stand up to high compressive forces required for grazing diet
  • Broad flat skulls, powerful jaw muscles
  • Small, acidic stomach; simple digestive tract; microbial fermentation in hindgut (Barboza 1993)
• Adaptations to small home range with limited/variable food and water (Johnson 1998)
  • Energetically frugal lifestyle - extremely low energy use for a mammal (Evans et al. 2003)
  • Metabolic and digestive strategies (Barboza 1993; Evans et al. 2003; Johnson 1998)
    • Low requirements for energy and nitrogen, low metabolic rates (Hume & Barboza 1998)
      • Northern hairy-nosed wombat most extreme in one study (Evans et al. 2003)
        • FMR (food intake necessary for energy expended) only 40% of value predicted for mammal of similar size
        • Varies seasonally - dry season FMR about half that of wet season
    • Digestion differs between species - adapted to variations in food quantity and quality in different habitats
      • Common wombat - high-capacity digestive tract to extract energy from large amounts of low-quality food
      • Hairy-nosed wombats - can extract energy from less food as it moved slowly through long digestive tract

• Water use strategies (Evans et al. 2003)
• Use less water than other marsupials
  • Far below predicted value for herbivorous mammal of comparable size
  • Northern hairy-nosed wombat water flux rate one of lowest for any mammal (25% of predicted value)
• Lack sweat glands
  • Conserves water but increases susceptibility to heat stress
• Common wombat has thick, coarse fur to cope with low temperatures
  • One of few marsupials active above snowline in winter
• Defensive adaptations
  • Posterior has pronounced slope, extremely tough skin, tiny tail
  • Threatened wombat blocks burrow entrance by standing with head in and rear out
• Adaptations for semi-fossorial (burrowing) lifestyle
  • Short, stout, muscular front legs with long, flat claws on forefeet - effective for digging
  • Rear-opening pouch with opening controlled by sphincter muscle - minimizes dirt entry (Triggs 1996)
  • High tolerance for hypoxia/hypercapnia (low oxygen/high CO2 levels in blood) (Steele & Temple-Smith 1998)
    • Allows wombats to spend extended time in burrows with limited air circulation
    • Southern hairy-nosed wombat study - severe respiratory challenges encountered in burrow (Shimmin et al. 2001-2002):
      • Unoccupied burrows - 20.9% O2, 0.04% CO2 (similar to outside)
      • Occupied burrows - as low as 16.3% O2, as high as 2.6% CO2

• Senses & nervous system (Triggs 1996; Wells 1987)
  • Poor eyesight, good hearing, keen sense of smell (based on observation, not confirmed)
  • Large brain
• Digestive system (Barboza 1993)
  • Plant cell contents digested in small, acidic stomach and simple small intestine
    • Stomach very small compared to most herbivores
    • Lining organized into specialized cardio-gastric gland - multiple pouches open into stomach through 25-30 large holes
  • Plant cell walls digested by hind-gut fermentation (similar to koalas, different from kangaroos)
    • Large colon packed with dense population of bacteria
    • Food particles pass through very slowly, giving time for breakdown by microbial fermentation
      • Average time 52-62 h in one study (Barboza 1993)
• Urogenital system (Triggs 1996)
  • Cloaca - urine and feces released from single posterior opening, as in all marsupials
  • Female reproductive organs
    • 2-horned uterus
    • Rear-opening pouch contains 2 teats
  • Male reproductive organs
    • Testes in heart-shaped scrotum suspended from lower abdomen
    • Penis bifurcated (branched) at end with backward-facing spines; stored retracted in body (Wells 1987)

Wombats have round, stocky bodies adapted for living underground.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Wombats have strong toenails for digging. These nails are present even early in development.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Barboza (1993)
Evans et al. (2003)
Horsup & Johnson (2008)
Hume (1999)
Hume & Barboza (1998)
Johnson (1998)
McIlroy (2008)
Menkhorst & Knight (2011)
Moeller (1990)
Murray (1998)
Steele & Temple-Smith (1998)
Taggart & Temple-Smith (2008)
Triggs (1996)
Wells (1987)