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8 Fun Facts About the Fossa

Closeup of a Fossa
Mathias Appel / CC0

The upcoming version of Ubuntu is codenamed “Focal Fossa,” the latest in a long list of software tools and programming languages named after animals. But what is a fossa, anyway?

These huge mongoose relatives are found in just one place in the world, and aren’t quite like any other animal—so it’s no surprise if you haven’t heard of them. Here are the coolest things to know about the latest tech-industry mascot.

What Is a Fossa?

Although they’re related to mongooses, fossas (pronounced “FOO-sahs”) look more like weird, slinky cats than like their mongoose cousins. But at up to six feet long from nose to the tip of the tail, they’re a lot bigger than your average cat.

Fossas live on the east African island of Madagascar. Over millions of years, this island has developed unique ecosystems and equally unique wildlife—92 percent of the mammals on Madagascar aren’t found anywhere else in the world, including fossas.

Fossas occupy the top of the Madagascar food chain. Using retractable claws and sharp teeth, they hunt just about anything they please. However, fossas today are threatened by human activity on the island, which has destroyed much of their natural habitat.

Our Favorite Fossa Facts

Fossa standing on rock in full profile
Ran Kirlian / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

Millions of years of island evolution have provided the fossa with some pretty interesting traits. Here are some fascinating facts about these catlike hunters.

Fossas Are Mostly Tail

Fossas clock in at about six feet long—an impressive length, but a solid half of that is tail. These forest predators spend a lot of time navigating Madagascar’s treetops, where their long tails get lots of use. A fossa tail can serve as a balancing aid on a shaky branch, allowing fossas to move even faster than their favorite prey: lemurs.

Lemurs Depend on Fossas

As the fossa’s favorite snack, you might think that lemurs are threatened by fossas. But while an individual lemur might perish at a fossa’s paws, the fate of the lemur species actually depends on these predators.

Without natural predators, lemur populations on the island would grow out of control. An out-of-control population will quickly use up all its habitat and food resources, putting the whole species under threat. So without fossas to hunt them, Madagascar’s lemurs probably wouldn’t survive.

Fossas Are Fast Killers

A lemur facing death by fossa won’t have much time to contemplate its fate. Fossas kill by using their impressive teeth to bite right through their prey’s skull.

We Don’t Know How Many Fossas There Are

There’s no doubt that fossa populations are shrinking along with their habitats. However, scientists aren’t quite sure how many fossas are left in the island forests, although it’s estimated to be around 2,500. In fact, we don’t know much about fossas at all.

Fossas whip through the trees quickly, making them hard to find and observe. They’re mostly solitary, so there are no fossa groups that can be tracked. Plus, their reddish-brown coats all look more or less the same—there are no striped or spotted patterns to distinguish one fossa from the next. This makes researching the fossa difficult. Researchers thought they were nocturnal until relatively recently, but it turned out they were just good at hiding.

However, it’s safe to say there aren’t too many of them. In addition to facing habitat threats, fossas simply don’t reproduce very fast. Females give birth just once a year to litters of two to four pups. It takes three years for a fossa to reach adulthood and four before they’re ready to have pups of their own.

Fossas Purr Like Cats

Although they aren’t cats, fossas do purr, at least when they’re young. Fossa pups have been found to make a purr-like sound when they’re around their mother. The pups are also born with white fur, which starts to turn brown when they’re two to three weeks old.

Young Female Fossas Have Fake Penises

Yes, you read that right. Masculinization in females is a unique feature of just a few mammal species, and female fossas experience something even rarer, called transient masculinization.

Before reaching sexual maturity, female fossas grow enlarged, spiny clitorises that mimic the male penis. This is thought to protect female fossas from the persistent advances of mating males until they’re old enough to mate. As they get older, the females lose these “masculine” traits.

Female Fossas Are Choosy

When it is time to choose a mate, female fossas remain in control of the situation. A female in heat will climb high up in a tree and wait while the males on the ground fight for the chance to mate with her. She’ll choose her mate from the winners, and once they’re done mating, she’ll leave her chosen treetop to a new female, where the mating ritual will begin again. Fossas often return to the same tree to mate year after year.

The Fossa’s Scientific Name Has a Surprising Translation

Scientifically, fossas are known as Cryptoprocta ferox. Ferox translates to “fierce,” which isn’t surprising for these fierce hunters. But Cryptoprocta translates to “hidden anus.” The name references another weird fossa feature: a natural pouch covers their anuses.


It’s not hard to see why the resourceful, unique fossa was chosen for the latest Ubuntu codename. However, without serious conservation efforts, the fossa runs the risk of dying out like obsolete software. With so much left to learn about fossas, here’s hoping that they’ll be protected for years to come.

Elyse Hauser Elyse Hauser
Elyse Hauser is a Seattle-based writer and editor with a Master's in Writing Studies from Saint Joseph's University. Her work has appeared in publications like Racked, Vine Leaves Literary Journal, and Rum Punch Press. She was awarded a 2017 Writing Between the Vines residency.  Read Full Bio »