Carnivore Reserve

Verified Timeline

Lore & Background

The fossa's taxonomic classification has been controversial because its physical traits resemble those of cats, yet other traits suggest a close relationship with viverrids. Edward Turner Bennett formally described the fossa in 1833 from a specimen sent by Charles Telfair. Bennett originally placed it as a type of civet in the family Viverridae. In 1939, William King Gregory and Milo Hellman placed the fossa in its own subfamily within Felidae, the Cryptoproctinae. George Gaylord Simpson placed it back in Viverridae in 1945. In 1993, a DNA hybridization study by Géraldine Veron and François Catzeflis suggested the fossa was more closely related to mongooses (family Herpestidae). In 2003, molecular phylogenetic studies by Anne Yoder and colleagues showed all native Malagasy carnivorans share a common ancestry and are most closely related to Asian and African Herpestidae. All Malagasy carnivorans are now placed in a single family, Eupleridae, with the fossa in the subfamily Euplerinae. An extinct relative, Cryptoprocta spelea, was described in 1902 from subfossil remains and was larger than the living fossa, with a body mass estimate roughly twice as great. Across Madagascar, people distinguish two kinds of fossa—a large fosa mainty ("black fossa") and the smaller fosa mena ("reddish fossa")—and a white form has been reported in the southwest.

In Their Own Story

The fossa appears as a diminutive form of a large felid, such as a cougar, but with a slender body and muscular limbs, and a tail nearly as long as the rest of the body. It has a mongoose-like head, relatively longer than that of a cat, with a broad and short muzzle and large but rounded ears. Its head-body length is 70–80 cm and its tail is 65–70 cm long. Adult males weigh 6.2–8.6 kg, females 5.5–6.8 kg. Smaller individuals are typically found north and east on Madagascar, larger ones to the south and west. Unusually large individuals weighing up to 20 kg have been reported, but there is some doubt as to the reliability of the measurements. Both sexes have short, straight fur that is relatively dense and without spots or patterns, generally reddish-brown dorsally and dirty cream ventrally. Juveniles are either gray or nearly white. The fossa has semi-retractable claws and very flexible ankles that allow it to readily grasp tree trunks to climb up or down trees head first or leap to another tree. Captive juveniles have been known to swing upside down by their hindfeet from knotted ropes. The male fossa has an unusually long penis and baculum, reaching to between his forelegs when erect, with an average thickness of 20 mm. The female fossa exhibits transient masculinization, starting at about 1–2 years of age, developing an enlarged, spiny clitoris that resembles a male's penis, supported by an os clitoridis which decreases in size as the animal grows.

Reader's Guide

The fossa is the largest mammalian carnivore on Madagascar. Adults have a head-body length of 70–80 cm and weigh between 5.5 and 8.6 kg, with males larger than females. It has semi-retractable claws and flexible ankles that allow it to climb up and down trees head-first and jump from tree to tree. The species is widespread, although population densities are usually low. It is found solely in forested habitat and actively hunts both by day and night. Over 50% of its diet consists of lemurs; tenrecs, rodents, lizards, birds, and other animals are also documented as prey. Mating usually occurs in trees on horizontal limbs and can last for several hours. Litters range from one to six pups, which are born altricial (blind and toothless). Infants wean after 4.5 months and are independent after a year. Sexual maturity occurs around three to four years of age, and life expectancy in captivity is 20 years. The fossa is listed as a vulnerable species on the IUCN Red List. It is generally feared by the Malagasy people and is often protected by their fady taboo. The greatest threat to the fossa is habitat destruction.

Did You Know?

• The fossa's generic name Cryptoprocta refers to how its anus is hidden by its anal pouch, from the Ancient Greek words crypto- 'hidden' and procta 'anus'.
• The female fossa exhibits transient masculinization, developing an enlarged, spiny clitoris that resembles a male's penis, which decreases in size as the animal grows.
• The fossa has semi-retractable claws, meaning it can extend but not retract its claws fully.
• A larger relative, Cryptoprocta spelea, probably became extinct before 1400 and had a body mass estimate roughly twice as great as the living fossa.
• The fossa is unique within its family for the shape of its genitalia, which share traits with those of cats and hyenas.