Madagascar is a strange place. Since it’s an island, and a big one, the flora and fauna of Madagascar are very unique, and sometimes very strange. I am sure more Malagasy animals will make their way onto this blog, but for today we will focus on the largest Malagasy Carnivore, the fossa.

The classification of the fossa has been an issue ever since the animal was first discovered. It was originally thought that the fossa was a felid, thanks to its appearance. Others placed the fossa with the civets, in the family Viverridae. Currently, all Malagasy Carnivores are classified in the family Eupleridae, with their closest relatives being the mongooses.

A very pensive looking fossa.
Image by Bertal, CC BY-SA 3.0, via Wikimedia Commons

Fossas range in size from 60 to 80 cm, and can weigh up to twenty kilograms. They have blunt snouts with large eyes, and very long whiskers. Fossas also have cat-like retractable claws (though they cannot be fully retracted), that help them climb trees. Unlike cats, fossas have very flexible ankles, which allows them to go up and down trees head first. Fossas have reddish-brown fur, and a long tail that helps them balance when they are in trees.

Fossas have a semi-arboreal lifestyle, in part because their main source of food, lemurs, are adept climbers. Fossas will also hunt on the ground, capturing snakes, small mammals, and guinea fowl. Due to fossas being the largest predators on Madagascar, they only really have to worry about predation from humans.

One of the strangest things about fossas is their reproductive habits. When a female fossa gets in the mood, she climbs a tree, beneath which a slew of male fossas congregate. They call to her loudly, and also try and get her attention through fights with one another. She chooses a male to mate with, and copulation often takes place in the tree, which would be tricky at the best of times, but is made more difficult by the male fossa’s large, spiked penis.

That’s right, male fossas have a penis with backward-facing spines, that stick out when erect, and lock the two fossas together for an extended period of time (sometimes up to 160 minutes!!). After she’s done with one male, the female will pick another to mate with. She will stay in her tree and mate for about a week, at which point another female will take over the site.

Females give birth to two to four pups, that are weaned around 20 months of age, and reach full size at four years old. Young female fossas go through a very strange period of masculinization at adolescence, in which the clitoris develops into a penis-like structure, including the spines that are so prominent in male fossas. As the female gets older, this penis shrinks, and by the time she is sexually mature, the pseudopenis disappears.

Fossas are certainly very strange animals — they look fairly innocent, but no truly innocent animal would have a spiked penis. Still, at least they are interesting. I just wouldn’t want to be a female fossa.

Cover image by Rod Waddington, CC BY-SA 2.0, via Wikimedia Commons, cropped to fit