Thanks to Mia for suggesting the black rhino this week! We'll also learn about other rhinos and their relations, including a mystery rhino.

Further reading:

Photos suggest rhino horns have shrunk over past century

The Blue Rhinoceros - In Quest of the Keitloa

A rhino with a very small third horn:



Some rhinos have really big second horns [photo by David Clode and taken from this site]:



The "blue rhinoceros," or keitloa, as illustrated in the mid-19th century:



Show transcript:
Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.
This week we’re going to talk about an animal I can’t believe we haven’t covered before. Thanks to Mia for suggesting the rhinoceros, specifically the black rhino! We’ll also learn about a mystery rhino.
We’ve talked about elephants lots of times, hippos quite a few times, and giraffes a couple of times, but pretty much the only episodes where we discussed a rhinoceros were 5 and 256. Episode 256 was mostly about mammoths, although we talked very briefly about the woolly rhinoceros, while episode 5 was about the unicorn and didn’t actually specifically talk about the rhino. So after almost 350 episodes of this podcast, one of the most amazing animals alive is one we literally haven’t learned about! Let’s fix that now.
Most people are pretty familiar with what a rhinoceros looks like. Basically, it’s a big, heavy animal with relatively short legs, a big head that it carries low to the ground like a bison, and at least one horn that grows on its nose. It’s usually gray or gray-brown in color with very little hair, and its skin is tough. It eats plants.
The rhinoceros isn’t related to the elephant or the hippopotamus. It’s actually most closely related to the horse and the tapir, which are odd-toed ungulates. The rhino has three toes on each foot, with a little hoof-like nail covering the front of each toe, but the bottom of the rhino’s foot is a big pad similar to the bottom of an elephant’s foot.
The rhino’s nose horn isn’t technically a horn because it doesn’t have a bony core. It’s made of long fibers of keratin all stuck together, and keratin is the same protein that forms fingernails and hair. That makes it even weirder that some people think a rhinoceros horn is medicine. It’s literally the same protein as fingernails, and no one thinks of fingernails are medicine. The use of rhinoceros horn as medicine isn’t even all that old. Ancient people didn’t think it was medicine, but some modern people do, and they’ll pay a whole lot of money for part of a rhino horn to grind up and eat. Seriously, they might as well be eating ground-up fingernails. (That’s gross.)
Because rhino horns are so valuable, people will kill rhinos just to saw their horns off to sell. That’s the main reason why most species of rhino are so critically endangered, even though they’re protected animals. Sometimes conservationists will sedate a wild rhino and saw its horn off, so that poachers won’t bother to kill it. A 2022 study determined that the overall size of rhino horns has shrunk over the last century, probably for the same reason that many elephants now have overall smaller tusks. Poachers are more likely to kill animals with big horns, which means animals with smaller horns are more likely to survive long enough to breed.
The species of rhinoceros alive today are native to Africa and Asia, but it used to be an animal found throughout Eurasia and North America. It’s one of the biggest animals alive today, but in the past, some rhinos were even bigger. We’ve talked about Elasmotherium before, which lived in parts of Eurasia as recently as 39,000 years ago. It had long legs and could probably gallop like a horse, but it was the size of a mammoth. It also probably had a single horn that grew in the middle of its forehead, which is why it’s sometimes called the Siberian unicorn.
We’ve also talked about Paraceratherium before. It was one of the biggest land mammals that ever li...