The scientific name for the horse is Equus ferus caballus. Modern day horses are one of seven species descended from the Equidae. Different breeds of horses exist, bred for different tasks with different personalities and traits. Other species that are descended from the Equidae and closely related to horses are Equus asinus (the donkey), Equus zebra (the mountain zebra), and Equus burchelli (the plains zebra). Horses can crossbreed with other members of the genus equus in the equidae family. The most common is mule, a cross between a male donkey and a mare.