If you’re a subscriber on Patreon, you may recognize some of the information in this episode, but I’ve updated it and added a whole bunch. Thanks to Pranav for the topic suggestion!

A cama, llama/camel hybrid:

A swoose, swan/goose hybrid:

Motty the Asian/African elephant hybrid and his mother:

A zorse, zebra/horse hybrid:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’ve got another listener suggestion. Pranav really really wants me to do an episode about hybrid animals, but I’ve been dragging my feet on it because I actually already did an episode on the topic back in 2017—but only for Patreon subscribers. It wasn’t my best episode so for various reasons I’d decided not to unlock it. But Pranav really really wants to learn about hybrids! So I’ve taken part of the Patreon episode and added a lot of newer information to it to bring it up to date and make it more interesting.

The term for an animal with parents of different species is hybrid. Crossbreed is also a common term, although technically a crossbred animal is one with parents of the same species but different breeds, like a labradoodle is a crossbreed of a Labrador and a poodle. Both parents are domestic dogs.

A mule, on the other hand, is a hybrid between a horse and a donkey, specifically a mare and a jack, which is what a male donkey is called. The offspring of a stallion and a lady donkey, known as a jenny, is a hinny.

So why can a horse and a donkey breed while, for instance, a possum and a rat can’t? The two species must belong to the same family, and with very few exceptions, they must also belong to the same genus. The genus is indicated in an animal’s scientific name. Equus caballus is a horse and Equus africanus is a donkey, while a Labrador and a poodle are both Canis familiaris, or Canis lupus familiaris depending on who you ask. The Virginia opossum is Didelphis virginiana while the brown rat is Rattus norvegicus. They’re not even slightly related, although superficially they look alike.

If the hybrid’s parents are from species with different numbers of chromosomes, hybrid males will almost always be sterile. You can’t cross two mules to get more mules, for instance, because male mules can’t make babies. Female mules are sometimes fertile but very rarely conceive. Horses have 64 chromosomes while donkeys have 62. Mules end up with 63. Hinnies are much rarer than mules because if the female of a pair of related species has fewer pairs of chromosomes than the male, it’s less likely that any offspring will result.

More closely related species can have fertile offspring. Killer bees, for instance, are hybrids of a European honeybee and an African honeybee. The two are actually subspecies of the honeybee, Apis mellifera, so it’s less like creating a hybrid and more like crossing a Labrador and a poodle to get an adorable happy pup with curly hair. It seemed like a really good idea. The result was supposed to be a tropical bee that would produce more honey. What actually happened was killer bees. Which do actually kill people. Hundreds of people, in fact, since they escaped into the wild in 1957 and started spreading throughout the Americas.

When animals hybridize even though they aren’t of the same genus, it’s called an intergeneric hybrid. That’s the case with sheep and goats. While sheep and goats are related on the subfamily level, they belong to separate genuses. Sheep have 54 chromosomes while goats have 60. That’s enough of a difference that most hybrid babies don’t survive long enough to be born alive, but it does happen occasionally. Usually the babies have 57 chromosomes, and sometimes the babies survive and even prove to be fertile when crossed with either a goat or a sheep. So that’s weird.

Just because someone wants to find out what you get when you cross, say, a sheep and a goat, doesn’t mean the sheep and goat in question are willing to make th...