Colugo
Encyclopedia
Colugos are arboreal gliding mammal
s found in South-east Asia. There are just two extant species
, which make up the entire family
Cynocephalidae (icon) and order
Dermoptera. They are the most capable of all gliding mammals, using flaps of extra skin between their legs to glide from higher to lower locations. They are also known as cobegos or flying lemurs, though they are not true lemur
s.
or a very large squirrel
. They have moderately long, slender limbs of equal length front and rear, a medium-length tail, and a relatively light build. The head is small, with large, front-focused eyes for excellent binocular vision, and small, rounded ears. When born, a colugo weighs only about 35 g (1.2 oz) and does not reach adult size for 2–3 years.
Their most distinctive feature is the membrane of skin that extends between their limbs and gives them the ability to glide long distances between trees. Of all the gliding mammals, the colugos have the most extensive adaptation to flight. Their gliding membrane, or patagium
, is as large as is geometrically possible: it runs from the shoulder blades to the fore-paw, from the tip of the rear-most finger to the tip of the toes, and from the hind legs to the tip of the tail; unlike in other known gliding mammals, even the spaces between the fingers and toes are webbed to increase the total surface area, as in the wings of bat
s. As a result, colugos were traditionally considered being close to the ancestors of bats, but are now seen by some as the closest living relatives to primate
s.
They are surprisingly clumsy climbers. Lacking opposable thumbs and not being especially strong, they proceed upwards in a series of slow hops, gripping onto the bark of trees with their small, sharp claws. They are as comfortable hanging underneath a branch as sitting on top of it. In the air, however, they are very capable, and can glide as far as 70 metres (230 feet) from one tree to another with minimal loss of height.
Colugos are shy, nocturnal, and restricted to the tropical rainforest
s of Southeast Asia. In consequence, remarkably little is known about their habits, although they are believed to be generally solitary, except for mothers nursing young. They are certainly herbivore
s, and are thought to eat mostly leaves, shoots, flowers and sap, and probably fruit as well. They have well-developed stomachs and long intestine
s, capable of extracting nutriment from leaves.
The incisor
teeth of colugos are highly distinctive; they are comb-like in shape, with up to twenty tines on each tooth. The second upper incisors have two roots, another unique feature among mammals. The function of these adaptations is not currently known. The dental formula
of colugos is:
Although they are placental mammals, colugos are marsupial
-like in their breeding habits. The young are born after 60 days of gestation in a tiny and undeveloped form, and spend their first six months or so of life clinging to the mother's belly. To protect them and transport them she curls her tail up to fold the gliding membrane into a warm, secure quasi-pouch. Breeding is fairly slow as the young do not reach full size until they are two or three years old.
, and the Philippine Flying Lemur
was classified by the IUCN as vulnerable at one time.The IUCN 1996 had declared the species vulnerable due to destruction of lowland forests and hunting. It was downlisted to least concerns in 2008 but still under the same threats as before. In addition to the ongoing clearing of its rainforest habitat, it is hunted for its meat and fur. It is also hunted by the gravely endangered Philippine Eagle
: some studies suggest that colugos account for 90% of the eagle's diet. It is not known how the diurnal eagles catch so many of the nocturnal colugos, which are thought to spend the greater part of the day curled up in tree hollows or hanging inconspicuously underneath a branch.
The Mixodectidae
appear to be fossil Dermoptera. However although other Paleogene
mammals have been interpreted as related to Dermopterans, the evidence for this is uncertain and many of them are no longer interpreted as being gliding mammals. At present, the fossil record of definitive dermopterans is limited to two species of the Eocene
and Oligocene
cynocephalid genus Dermotherium
.
Recent molecular phylogenetic
studies have demonstrated that colugos belong to the clade
Euarchonta
along with the treeshrew
s (order Scandentia) and the primates, with the colugos more closely related to primates. In this taxonomy, the Euarchonta
are sister to the Glires
(lagomorphs
and rodent
s), and the two groups are combined into the clade
Euarchontoglires
.
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s found in South-east Asia. There are just two extant species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, which make up the entire family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Cynocephalidae (icon) and order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Dermoptera. They are the most capable of all gliding mammals, using flaps of extra skin between their legs to glide from higher to lower locations. They are also known as cobegos or flying lemurs, though they are not true lemur
Lemur
Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species...
s.
Characteristics
Colugos are fairly large for a tree-dwelling mammal: at about 35 to 40 cm (13.8 to 15.7 in) in length and 1 to 2 kg (2.2 to 4.4 ) in weight, they are comparable to a medium-sized possumPossum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...
or a very large squirrel
Squirrel
Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...
. They have moderately long, slender limbs of equal length front and rear, a medium-length tail, and a relatively light build. The head is small, with large, front-focused eyes for excellent binocular vision, and small, rounded ears. When born, a colugo weighs only about 35 g (1.2 oz) and does not reach adult size for 2–3 years.
Their most distinctive feature is the membrane of skin that extends between their limbs and gives them the ability to glide long distances between trees. Of all the gliding mammals, the colugos have the most extensive adaptation to flight. Their gliding membrane, or patagium
Patagium
*In bats, the skin forming the surface of the wing. It is an extension of the skin of the abdomen that runs to the tip of each digit, uniting the forelimb with the body.*The patagium of a bat has four distinct parts:...
, is as large as is geometrically possible: it runs from the shoulder blades to the fore-paw, from the tip of the rear-most finger to the tip of the toes, and from the hind legs to the tip of the tail; unlike in other known gliding mammals, even the spaces between the fingers and toes are webbed to increase the total surface area, as in the wings of bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s. As a result, colugos were traditionally considered being close to the ancestors of bats, but are now seen by some as the closest living relatives to primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s.
They are surprisingly clumsy climbers. Lacking opposable thumbs and not being especially strong, they proceed upwards in a series of slow hops, gripping onto the bark of trees with their small, sharp claws. They are as comfortable hanging underneath a branch as sitting on top of it. In the air, however, they are very capable, and can glide as far as 70 metres (230 feet) from one tree to another with minimal loss of height.
Colugos are shy, nocturnal, and restricted to the tropical rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s of Southeast Asia. In consequence, remarkably little is known about their habits, although they are believed to be generally solitary, except for mothers nursing young. They are certainly herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s, and are thought to eat mostly leaves, shoots, flowers and sap, and probably fruit as well. They have well-developed stomachs and long intestine
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
s, capable of extracting nutriment from leaves.
The incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
teeth of colugos are highly distinctive; they are comb-like in shape, with up to twenty tines on each tooth. The second upper incisors have two roots, another unique feature among mammals. The function of these adaptations is not currently known. The dental formula
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
of colugos is:
Although they are placental mammals, colugos are marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
-like in their breeding habits. The young are born after 60 days of gestation in a tiny and undeveloped form, and spend their first six months or so of life clinging to the mother's belly. To protect them and transport them she curls her tail up to fold the gliding membrane into a warm, secure quasi-pouch. Breeding is fairly slow as the young do not reach full size until they are two or three years old.
Status
Both species are threatened by habitat destructionHabitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
, and the Philippine Flying Lemur
Philippine Flying Lemur
The Philippine Flying Lemur is one of two species of flying lemurs, the only two living species in the order Dermoptera. Additionally, it is the only member of the genus Cynocephalus.-Distribution:...
was classified by the IUCN as vulnerable at one time.The IUCN 1996 had declared the species vulnerable due to destruction of lowland forests and hunting. It was downlisted to least concerns in 2008 but still under the same threats as before. In addition to the ongoing clearing of its rainforest habitat, it is hunted for its meat and fur. It is also hunted by the gravely endangered Philippine Eagle
Philippine Eagle
The Philippine Eagle , also known as the Monkey-eating Eagle, is an eagle of the family Accipitridae that is endemic to forests in the Philippines. It has brown and white-coloured plumage, and a shaggy crest, and generally measures in length and weighs...
: some studies suggest that colugos account for 90% of the eagle's diet. It is not known how the diurnal eagles catch so many of the nocturnal colugos, which are thought to spend the greater part of the day curled up in tree hollows or hanging inconspicuously underneath a branch.
Classification and evolution
- ORDER DERMOPTERA
- Family Cynocephalidae
- Cynocephalus
- Philippine Flying LemurPhilippine Flying LemurThe Philippine Flying Lemur is one of two species of flying lemurs, the only two living species in the order Dermoptera. Additionally, it is the only member of the genus Cynocephalus.-Distribution:...
, Cynocephalus volans
- Philippine Flying Lemur
- Galeopterus
- Sunda Flying LemurSunda Flying LemurThe Sunda Flying Lemur , also known as the Malayan Flying Lemur, is a species of colugo . Until recently, it was thought to be one of only two species of flying lemur, the other being the Philippine Flying Lemur which is found only in the Philippines...
, Galeopterus variegatus
- Sunda Flying Lemur
- †DermotheriumDermotheriumDermotherium is a genus of fossil mammals closely related to the living colugos, a small group of gliding mammals from Southeast Asia. Two species are recognized: D. major from the Late Eocene of Thailand, based on a single fragment of the lower jaw, and D. chimaera from the Late...
- †Dermotherium major
- †Dermotherium chimaera
- Cynocephalus
- Family Cynocephalidae
The Mixodectidae
Mixodectidae
Mixodectidae or mixodectids is an extinct family of insectivore, placental mammals in the order Dermoptera....
appear to be fossil Dermoptera. However although other Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
mammals have been interpreted as related to Dermopterans, the evidence for this is uncertain and many of them are no longer interpreted as being gliding mammals. At present, the fossil record of definitive dermopterans is limited to two species of the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
and Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
cynocephalid genus Dermotherium
Dermotherium
Dermotherium is a genus of fossil mammals closely related to the living colugos, a small group of gliding mammals from Southeast Asia. Two species are recognized: D. major from the Late Eocene of Thailand, based on a single fragment of the lower jaw, and D. chimaera from the Late...
.
Recent molecular phylogenetic
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
studies have demonstrated that colugos belong to the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
Euarchonta
Euarchonta
The Euarchonta are a grandorder of mammals containing four orders: the Dermoptera or colugos, the Scandentia or treeshrews, the extinct Plesiadapiformes, and the Primates....
along with the treeshrew
Treeshrew
The treeshrews are small mammals native to the tropical forests of Southeast Asia. They make up the families Tupaiidae, the treeshrews, and Ptilocercidae, the pen-tailed treeshrews, and the entire order Scandentia. There are 20 species in 5 genera...
s (order Scandentia) and the primates, with the colugos more closely related to primates. In this taxonomy, the Euarchonta
Euarchonta
The Euarchonta are a grandorder of mammals containing four orders: the Dermoptera or colugos, the Scandentia or treeshrews, the extinct Plesiadapiformes, and the Primates....
are sister to the Glires
Glires
Glires is a clade consisting of rodents and lagomorphs . This hypothesis that these form a monophyletic group has been long debated based on morphological evidence, although recent morphological studies strongly support monophyly of Glires...
(lagomorphs
Lagomorpha
The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families, the Leporidae , and the Ochotonidae...
and rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s), and the two groups are combined into the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
Euarchontoglires
Euarchontoglires
Euarchontoglires is a clade of mammals, the living members of which are rodents, lagomorphs, treeshrews, colugos and primates .-Evolutionary relationships:...
.