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

*(Churcher 1993)

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)

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)

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

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

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 Wildlife Alliance. All rights reserved.

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