Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Equus (comics) been captured in the same story. Equus reappeared under Mr. Orr's command in "Countdown" #36 (2007), clashing with Karate Kid and Triplicate Girl. After receiving a beating from Karate Kid, Equus was enraged that Mr. Orr, under Desaad's orders, would let them go. Equus severs the railroad tracks on which Karate Kid and Triplicate Girl's train is traveling, after having phoned the police, telling them that the derailment is a metahuman attack, and that the metahumans themselves are bio-weapons, leading the officers to shoot first and not ask questions. Karate Kid and Una eventually are able to beat Equus, disabling