A zoo in northern Mexico recently welcomed an unusual animal into the world, a rare creature known as a zonkey, although also called a zedonk or donkra.

Zonkeys are a crossbreed between zebras and donkeys, and their rarity is marked by the fact that it had long been assumed that the chromosomes of the two different species could not mix.

The newborn zonkey, Khumba, born at Reynosa Zoo in the Mexican state of Tamaulipas on April 21, according to a story by the Fox News Latino, has black and white banded legs like a zebra, but the face, ears and fur of a donkey.

Last year in Italy, a zonkey named Ippo was born at a wildlife center for neglected and unwanted animals after its full-blooded zebra father acquired from a failing zoo, found a way past a fence intended to keep it from a female donkey.

Other zonkeys have reportedly been born in China, Germany, Georgia, Japan and the United States.

According to a study published in the journal Chromosoma, a donkey has 62 chromosomes while a zebra has between 32 and 46, depending on the specific species.

Yet, despite those differences, couplings between the two types of creatures have produced viable hybrids, thanks to gene combinations in the embryos that supported development until birth.

As it turns out, a zebra-donkey hybrid has a number of chromosomes somewhere in between the typical counts of the species.

The chromosome difference, however, usually leaves female hybrids poorly fertile and male hybrids sterile.

Zebra hybrids, or zebroids, physically resemble their non-zebra parent, but are striped like a zebra. The stripes generally do not cover the whole body, and might be confined to the legs or spread onto parts of the body or neck, as appears to be the case with the Khumba, newborn in Mexico.

Zebroids are preferred over zebras for practical uses, like riding, because the zebras have a different body shape from a horse or donkey and, as a result, it's difficult to find tack, or, riding implements, to fit a zebra.

On the flip side, a zebroid, the product of a wild zebra parent, is usually inclined to be more temperamental than a purebred horse and can be difficult to handle.