Swordwhale Walking: Illustration, stories, photojourneys, videos

Feet: Equines have one large toe; the hoof. Other hoofed animals have two toes (even-toed ungulates like cows, pigs, deer, antelope). Some other odd-toed ungulates (horses are odd-toed) have multiple toes (think tapir, elephant, rhino...rhinos are horse relatives).

It makes me nutz when someone draws a donkey or zebra with cloven hooves! WRONG!
 
Equines are: horse, donkey and zebra. 
   Ass, donkey and burro are the same critter.
   A mule is NOT a donkey!  A mule is a cross between a male donkey and a female horse (they look more or less like a large donkey...with a fuller tail).
   A hinny is a cross between a female donkey and a male horse (they look more horselike).
   A zonkey is a cross between a donkey and a zebra (they look like donkeys wearing striped stockings).
   A zorse is a cross between a zebra and a horse. (They look like very horselike, in regular horse colors, overlaid with stripes). Also called zebra mules.
   The crosses are usually sterile.
   A Przewalski horse is a rare, primitive, wild horse (looks like a cave painting). Scientists yet debate where it fits on the taxonomic tree; whether it is a separate species of equine (recent studies suggest it diverged from modern horses 160,000 years ago). It has 66 chromasomes, while the domestic horse has 64.Today's Przewalskis have some modern domestic DNA; crossed into the remaining Przwalskis to bring them back from the brink of extinction.
   A Tarpan is an extinct European wild horse. 20th century efforts to recreate it have produced the modern Tarpan.
   A quagga is an extinct subspecies of plains zebra (there are scientists trying to breed back to recreate them).
   Kiang, Onager, and African Wild Ass are wild (never domesticated) donkeys.
   A mustang is a feral horse (a wild horse with domestic ancestors). Types and bloodlines vary, but the original mustangs were brought to the Americas by the Spanish; the Spanish Colonial Horse.

Horse DNA creates two colors: red and black. A bunch of other totally confusing (some yet undiscovered) genes modify red and black into the rainbow of color that is horse.
   Then there's donkeys...
   ...and zebras...
   ...and the crosses.

It takes several websites to really describe horse color, so here's a few links...

Color basics:
To quote the mustang site, above, every horse is, at base, either red or black. A fantastic array of "modifiers" change those basics into...
Reds: chestnut/sorrel, bay, browns,
Blacks: some are jet-blue-black, most will have brownish overtones and sunbleach into something that looks like a weird dark bay, brown or even dun. Lor, left, is black.
Yellows: modifying genes dilute the other colors creating palominos (dilute of chestnut), cremellos (double dilute), buckskins (dilute of bay), perlino (double dilute). Duns, champagnes (several flavors) are created by different genes.
Whites: first of all, most of the white horses you see are actually grey: they started as some normal horse color and greyed (got more white hairs) as they matured. There are true white horses, but no albinos. Most other "white horses" are pintos with very minimal color, Appaloosas with almost no spots, or really pale dilutes like cremellos. Yataalii, below, is grey (look for the shot of him young and quite dark).
Greys: go from normal horse color to nearly or all white. They often go through a lovely dappled stage. Some end up "flea bitten" or "trout speckled" with tiny flecks of the original color in the white coat. Bazraf, below, is fleabitten grey. 
Spots:  Pintos (in several patterns like tobiano, overo, tovero, sabino, and splash) have a white maplike pattern thrown over a normal horse color. Appaloosas (and some other European breeds like the Knapstrupper) have an ancient dotted-splashed-snowflaked-marbled pattern of white thrown over a normal horse color. Magic, below, is leopard Appaloosa.
Zebra hybrids: now this just gets weird... the zebra stripes will only manifest in the horse's colored parts; a pinto's white areas are, well, white, so the hybrid will be a spotted horse with stripes inside the colored spots. Appaloosas are even more fun (oh, just google it!).

Horses have long legs to run from danger. Most of the muscles to power them are in the shoulders and haunches. The upper leg (forearm and gaskin) are fairly muscular (especially on heavily muscled horses like draft horses and quarter horses). The lower leg is mostly bone, skin and tendons; long and straight. Kids and cartoonists (I have a nifty Hairy Trotter T-shirt which exhibits this) often muck up the rear legs. Here's how they bend.