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Grevy's Zebra (Equus grevyi) Fact Sheet: Physical Characteristics

Physical Characteristics

AttributeMaleFemale
Body Weight* up to about 451kg (994 lb) 350 kg (772 lb)
Head and Body Length 2.5-3.0 m (8.2-9.8 ft) 2.5-3.0 m (8.2-9.8 ft)
Shoulder Height Average 1.35 m (4.4 ft) Average 1.35 m (4.4 ft)
Tail Length 55 cm (22 in) 55 cm (22 in)

*(Churcher 1993)

General Appearance

General

  • Body size and shape
    • Largest of the wild horses
    • Neck short and thick
    • Head very long and narrow
  • Head and facial features
    • Head very long and narrow
      • Long, thick and erect main of hair
        • Extends above the ears
    • Ears
      • Very large
      • Rounded with black markings
  • Legs and hooves
    • Small chestnuts (roughened skin patches) on the inner forelegs
    • Hooves small, broad, oval, and black
  • Tail
    • Cross-banded in the middle

Pelage

  • Narrow, black and white stripes
    • Narrowest and most tightly packed stripes of all the zebras (Bard 1977)
      • About 80 stripes in Grevy's
      • 25-30 in Plains
      • 43 in Mountain Zebras
    • Black stripe along spine
    • Bull's eye pattern on rump (Estes 1991)
    • Chevrons above the elbows and knees on fore and hind limbs
    • Stripes extend all the way down the legs, to the hooves
    • A band of white across the nose
    • Ash gray or white belly
  • Hair covers the muzzle
    • Long, coarse tactile hairs (vibrassae)

Sexual Dimorphism

Sexes similar

  • Males slightly larger than females
    • Males about 10% bigger (Ginsberg 1989)
  • Males with large upper canine teeth
    • Such teeth are typically lacking in females (Churcher 1993)

Adaptations

Body stripes

  • Possible explanations for their usefulness
    • Stripe pattern camouflages the zebra in moonlight (Churcher 1993)
      • Stripes make it unnoticeable when only 15 m (49 ft) away
    • Protection from tsetse flies - they prefer solid, dark colored targets (Waag 1981) (Ruxton 2002)
      • Idea discounted by Kingdon (2001): these flies not a problem in areas where Grevy's live
    • Predator avoidance - providing camouflage
    • Social benefits - recognition of species and individuals, promoting social bonds
    • Thermoregulation - black and white areas collect heat differently

Other Characteristics

Chromosome number (from Groves and Ryder 2000)

  • 23 pairs of chromosomes (2n=46)

Dentition (teeth)

  • 44 teeth in total
    • 6 incisors in upper jaws, 6 in lower jaws
    • 2 canines upper, 2 lower
    • 8 premolars upper, 8 lower
    • 6 molars upper, 6 lower

Many opinions about whether zebras are black with white stripes or white with black stripes

  • Black with white stripes
    • Gould (1981) and Prothero and Schoch (2002) cited embryological studies by Bard (1977) arguing zebras are black with white stripes:
      • Some evidence for this: an abnormal zebra born with rows of white dots for stripes (suggests "default' color was black; white stripes did not develop properly)
    • African native peoples view zebras as black with white stripes
    • Skin under hair is black
  • White with black stripes
    • Because the belly is white, many biologists suggest the animal should be considered white with black stripes.
      • Argument again this idea: a white belly is common counter shading in many otherwise dark colored animals, and shouldn't be used to justify having a white background color (Prothero 2002)
  • Stripes are both black and white
    • Carroll (2005) suggests zebras should be considered animals with both black and white stripes since both colors are controlled by genetic switches during development

Grevy's Zebra Stripes

Stripes on a Grevy Zebra

Stripes extend all the way down the legs, to the hooves. All individuals have a thick, erect mane of hair.

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Churcher (1993)
Estes (1991)
Gould (1981)
Groves & Ryder (2000)
Kingdon (1979, 2001)
Klingel (1990)
Ruxton (2002)

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