The Indriidae (sometimes incorrectly spelled Indridae) are a family of strepsirrhine

primate Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...

s. They are medium- to large-sized

lemur Lemurs ( ; from Latin ) are Strepsirrhini, wet-nosed primates of the Superfamily (biology), superfamily Lemuroidea ( ), divided into 8 Family (biology), families and consisting of 15 genera and around 100 existing species. They are Endemism, ...

s, with only four teeth in the toothcomb instead of the usual six. Indriids, like all lemurs, live exclusively on the island of

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

Classification

The 19 living species in the family are divided into three

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

. Family Indriidae *Genus ''

Indri The indri (; ''Indri indri''), also called the babakoto, is one of the largest living lemurs, with a head-body length of about and a weight of between . It has a black and white coat and maintains an upright posture when climbing or clinging. ...

'' **

, ''Indri indri'' *Genus '' Avahi'', woolly lemurs ** Bemaraha woolly lemur, ''Avahi cleesei'' ** Eastern woolly lemur, ''Avahi laniger'' ** Moore's woolly lemur, ''Avahi mooreorum'' ** Western woolly lemur, ''Avahi occidentalis'' ** Sambirano woolly lemur, ''Avahi unicolor'' ** Peyrieras's woolly lemur, ''Avahi peyrierasi'' ** Southern woolly lemur, ''Avahi meridionalis'' ** Ramanantsoavana's woolly lemur, ''Avahi ramanantsoavani'' ** Betsileo woolly lemur, ''Avahi betsileo'' *Genus '' Propithecus'', sifakas **''Propithecus diadema'' group *** Diademed sifaka, ''Propithecus diadema'' *** Silky sifaka, ''Propithecus candidus'' *** Milne-Edwards's sifaka, ''Propithecus edwardsi'' *** Perrier's sifaka, ''Propithecus perrieri'' *** Golden-crowned sifaka, ''Propithecus tattersalli'' **''Propithecus verreauxi'' group *** Verreaux's sifaka, ''Propithecus verreauxi'' *** Coquerel's sifaka, ''Propithecus coquereli'' *** Decken's sifaka, ''Propithecus deckenii'' *** Crowned sifaka, ''Propithecus coronatus''

Characteristics

The 19 extant Indriidae species vary considerably in size. Not counting the length of their tails, the avahis are only in length, while the

indri The indri (; ''Indri indri''), also called the babakoto, is one of the largest living lemurs, with a head-body length of about and a weight of between . It has a black and white coat and maintains an upright posture when climbing or clinging. ...

is the largest extant strepsirrhine. The tail of the indri is only a stub, while avahi and the sifaka tails are as long as their bodies. Their fur is long and mostly from whitish over reddish up to grey. Their black faces, however, are always bald. The hind legs are longer than their fore limbs, their hands are long and thin, and their thumbs cannot be opposed to the other fingers correctly. All species are

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

, though they do come to the ground occasionally. When on the ground, they stand upright and move with short hops forward, with their arms held high. In the trees, though, they can make extraordinary leaps and are extremely agile, able to change direction from tree to tree. Like most leaf eaters, they adjust for the low nutrient content of their food by long rests. Often, they can be seen lying stretched on trees sunning themselves. Indriidae live together in family federations up to 15 animals, communicating with roars and facial expressions. Indriidae are

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s, eating mostly leaves, fruits, and flowers. Like some other herbivores, they have a large

cecum The cecum ( caecum, ; plural ceca or caeca, ) is a pouch within the peritoneum that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the appendix (a ...

, containing

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

that ferment cellulose, allowing for more efficient

digestion Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into th ...

of plant matter. They have fewer

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

teeth than other lemurs, with the dental formula of: Females and males usually mate monogamously for many years. Mostly at the end of the dry season, their four- to five-month gestation ends with the birth of a single offspring, which lives in the family for a while after its weaning (at the age of five to six months).

References

{{Taxonbar, from=Q175626 Lemurs Folivores Primate families Taxa named by Gilbert Thomas Burnett Taxa described in 1821

Classification

Characteristics

See also

References