Giant glider

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Giant glider
Malay glider (Galeopterus variegatus)

Malay glider ( Galeopterus variegatus )

Systematics
Class : Mammals (mammalia)
Subclass : Higher mammals (Eutheria)
Superordinate : Euarchontoglires
without rank: Euarchonta
Order : Giant glider
Family : Giant glider
Scientific name of the  order
Dermoptera
Illiger , 1811
Scientific name of the  family
Cynocephalidae
Simpson , 1945

The giant gliders (Dermoptera), also known as fur Flitter , glider , Flattermakis or Colugos are one of the group of Euarchontoglires counting order of the higher mammals . The order includes a single living family (Cynocephalidae) with two species in two monotypical genera, the Philippines glider ( Cynocephalus volans ) and the Malaysian glider ( Galeopterus variegatus , synonymous with Cynocephalus variegatus ). Both species live in Southeast Asia and have an exclusively vegetable diet. They are about the size of a cat and with their characteristic flight membrane, which has a wingspan of 70–120 cm, can undertake long gliding flights.

The order of the giant gliders was established in 1811 by Johann Karl Wilhelm Illiger .

anatomy

General

Giant gliders are about the size of a cat, but built much lighter. Depending on the species, the total length is 56 to 69 centimeters with a head-trunk length of 34 to 42 centimeters and a tail length of 22 to 27 centimeters. The weight is usually 1 to 1.75 kilograms. The span is usually 70 centimeters, a maximum of 120 centimeters. On average, the Malaysian glider is larger than the Philippines glider, but the differences are minimal.

The largely bark-colored fur of the giant gliders has variable markings with white, brown and black spots on a gray to brown background. Front and rear limbs are roughly the same length and are very long and thin. The claws of the fingers are long and strong, the short thumb cannot be opposed to the other fingers. The greyhound-like pointed head gave the scientific name of the recent genus ( Cynocephalus = "dog's head"). The large eyes are about the same size as the relatively small ears .

Flying skin

Fur flutter from Brehms Thierleben , 1883

Characteristic of the giant gliders is the flight skin (patagium), with the help of which they are able to glide up to 70 meters. It consists of a skin membrane that is stretched between the neck and forelegs (neck fly skin, propatagium), fore and hind limbs (flank fly skin, plagiopatagium) and between the tail and hind limbs (tail fly skin, uropatagium). The limbs and tail are fully integrated into the flight membrane, only the claws of the fingers and toes protrude beyond it. The sections of the skin between the fingers and toes are called chiropatagium.

The flight membrane is hairy and colored gray or brown on the upper side and lightly spotted, the underside is light beige to bright orange and spotless. The surface of the flight membrane is much larger than that of other gliding mammals such as the glider and the glider .

Skull and teeth

The skull of the giant glider has no special features compared to the typical mammalian skull except the dentition. The snout region is flat and wide, there is no crest . The eye socket is not completely closed, the ring between the cheekbone and frontal bone is interrupted behind the eye. The skull is relatively small for the size of the animals. As a special feature of hearing , the eardrum is horizontal.

The 34 teeth of the glider are small, the tooth formula is 2 / 3–1 / 1–2 / 2–3 / 3. The highly specialized teeth of the giant glider are not like any other mammal and are specially adapted to their diet.

Similar to various types of ruminants, there are no teeth in the front upper jaw , the two incisors , the first of which is comparatively small, are on the side of the arch in front of the canines . The second upper incisor has two tooth roots ; this is unique among mammals. The incisors of the lower jaw and the canines are also double-rooted. The lower incisors form a tooth comb , a feature that is also found in a similar form in the wet-nosed monkeys . The tooth tips are accordingly divided into up to 20 tooth-like structures per tooth. The function of these teeth is still unknown, presumably they are used to filter tree sap or to improve the cleaning of the fur. The molars are triangular in shape and have five cusps.

Soft tissue anatomy

The stomach of the giant glider is elongated and sack-shaped and provided with additional diverticula in the rear area . It can digest large amounts of plant-based food very quickly and pass it on to the subsequent, relatively short small intestine . In order to utilize the hard-to-digest cellulose as much as possible, giant gliders have developed a long appendix (caecum) and the front area of ​​the large intestine is equipped with additional sacs. These house microorganisms that make difficult to digest parts usable. Overall, the intestines of the animals are up to nine meters long and thus around nine times as long as the animals themselves (head-trunk length).

The females are provided with a two-part uterus , a so-called uterus duplex . The testicles of the males are mostly located outside the abdominal cavity in the scrotum (scrotum), but can also be embedded in the groin region .

The muscles in the limbs are very strong, as various actions in connection with gliding, including the relaxation of the flight skin, require a lot of strength. The extensors outweigh the flexors. The flexors attach to the bone very far from the joints; this favorable arrangement saves energy and only enables the entire body to be spanned by the flight skin.

distribution and habitat

Distribution area of ​​the giant glider.
Red: Malay glider ( Galeopterus variegatus )
Green: Philippines glider ( C. volans ).

Giant gliders live in Southeast Asia . The distribution area of ​​the Malaysian glider includes southern Indochina , Thailand , Malaysia and western Indonesia to Borneo and Java , while the Philippines glider occurs only in the southern Philippines .

The two species living today inhabit tropical forests in their range. The Malaysian glider in particular can also be found in the region's coconut plantations.

Way of life

General

Giant gliders are predominantly nocturnal tree dwellers and rarely come to the ground. They spend the day in tree hollows or hanging from branches and tree trunks at heights of 25 to 50 meters. They particularly prefer tall and hollow trees on sloping slopes from which they can jump off quickly and slide far. They are very easy to scare away by knocking on the trees or making other loud noises, but in forest fires they usually stay on their tree and burn.

The nocturnal activity protects the animals from predators as many large predators such as the Philippine eagle are diurnal. When they hang on trunks or branches, the flight skin is usually spread out like a coat; in coconut plantations, giant gliders often roll up like a ball between palm fronds. When a bird of prey appears, they stretch the patagium and slip away.

At night they look for food, often gliding to familiar trees. Giant gliders are basically loners, but often several giant gliders feed on one tree at the same time. The area is around 6 to 13 hectares in size, but the territories overlap extensively. They are slow and clumsy climbers, but with their sloth - like claws they can move very well upside down on horizontal branches.

The vocalizations of giant gliders have not been researched very well, but little knowledge is available: The duck-like screams are mainly emitted by young animals, the vocalizations of the adults are very similar, but are only rarely uttered.

The glide

When a giant glider changes from one tree to another, it spreads its gliding membrane and jumps off the tree. With the help of stereoscopic vision , giant gliders can assess the landing point before a flight. The gliding flights normally take place over distances of 50 to 70 meters, but gliding flights of 100 meters and more have also been observed. During a record gliding flight of 136 meters, the loss of altitude was 12 meters. Further gliding flights may be possible, but this distance has been recorded as the largest to date. However, the animal is hardly able to influence the flight path with this mode of locomotion. As soon as it lands on the targeted tree, it climbs back up to compensate for the loss of height. Landing on the ground is always avoided.

nutrition

Giant gliders are pure herbivores that mainly eat flowers, leaves and buds, and more rarely also soft fruits or sap from trees. The plant food is usually pulled with the front paws in front of the mouth, where the food is then plucked off with the help of the strong tongue and the lower row of incisors. Similar to other tree dwellers, they obtain the liquid they need to survive from their food (especially when the leaves are wet, maximum moisture absorption is guaranteed) and from precipitation.

The emptying of the bowel is perpendicular hanging with far thrown back tail wing membrane as the animals due to the ventral ahead of the tail anus would otherwise pollute themselves.

Natural enemies

The slow movement in the canopy and the long gliding flights at low speed make giant gliders easy prey for birds of prey. The Philippine eagle ( Pithecophaga jefferyi ) is a particularly intensive giant glider hunter . Philippines gliders are among his main prey. It is estimated that 90% of its prey are giant gliders.

Reproduction and development

The gender differences in giant gliders are not noticeable. While the females tend to have gray coat tones, the males are more reddish-brownish. In addition, females are a little larger.

After a gestation period of around 60 days, usually one, rarely two young animals are born. At birth, these weigh around 35 grams and are noticeably underdeveloped - they are at a level of development that almost corresponds to that of newborn marsupials . They are saved by the mother in the folded sliding membrane and carried until weaning , which does not take place before the age of 6 months. Although the female glides less often during this time, this is possible because the uro patagium forms a pouch-like pocket between the hind limbs and tail in which the young can be transported. The young animal also clings to the flight membrane with its claws and its teeth to one of the mother's two teats . To sleep, the mother hangs on a branch like a sloth; the young animal then uses its mother as a sleeping place similar to a hammock.

Giant gliders compensate for the low number of young animals per litter with a high degree of regularity in reproduction; often the female is pregnant before she has weaned her previous young. Nothing is known about the age when they reach sexual maturity , but usually they are fully grown after two to three years, at least in terms of height. Little is known about the total age of life, but one animal has been shown to be at least 17.5 years old. General assumptions assume that giant gliders are durable.

Systematics

Tribal history

The order of the giant gliders has been documented in fossil records since the Paleocene and Eocene , but never achieved a large number of forms. Remnants of the early species Planetetherium mirabile were found in North America and come from the Upper Paleocene. Here Ellesmene occurred in the Lower Eocene to north of the Arctic Circle and was detected there in the Margaret Formation . At that time, however, the region was characterized by a warm to subtropical climate. Dermotherium from the Eocene of Thailand was already very similar to today's forms. In addition to the recent family, five other fossils have come down to us. A distinction is made here between the Plagiomenidae , Cyriacotheriidae , Thylacaelurinae and the Mixodectidae .

External system

The systematic classification of this group has long been controversial. They were viewed as relatives of insectivores or bats , and they were also assigned to primates and predators . This uncertainty was described in Brehms Thierleben as early as 1883:

“Linnaeus places them with the apes, Cuvier with the bats, Geoffroy with the beasts of prey, Oken with the beasts of prey, and finally Peters, probably rightly, with the carnivores, whose line they open. According to the researchers' uncertainty, the best-known species are still winged monkeys, fluttering lemurs, flying cats, wondrous bats, etc. "

On a morphological basis, it is obvious that the giant gliders are the sister taxons of the bats (Chiroptera), in which case both would form the taxon Volitantia . Both groups of animals share a number of characteristics that suggest a common ancestry. Both taxa have a flight membrane that continues between the fingers. In addition, there are fusions in the wrist ( fusion of the centrale , scaphoid and lunate to one bone) and a partial fusion of the forearm bones in the distal area. Both taxa contain a special muscle, the humeropatagialis muscle, in the tail flight membrane . In addition, the 4th and 5th toe rays are elongated and the tendons of the flexor are equipped with a passive holding mechanism. Further similarities can be found in the structure of the teeth, the muscles of the chest and the bony ear capsule .

On the basis of the comparison of the morphology of the middle ear of giant gliders and a primate of the genus Pleisiadapis from the Paleocene, it is possible to conclude that the giant gliders could be closely related to the primates . This assumption was first published in 1964 by Kai Simons . Later studies on the basis of mitochondrial DNA , which advocated a classification of the giant gliders within the primates as sister group of the Anthropoidea ("real monkeys") and would thus split them up as a natural taxon , could be refuted after the comparison of the mtDNA strands had been repeated and because DNA elements, which are found in all recent primate groups, are missing from the giant gliders. Molecular genetic studies from 2007 assigned the giant gliders to the Euarchontoglires , where they form the sister taxon of the primates. The similarities with the bats, which are therefore assigned to the Laurasiatheria , would in this case be regarded as convergent features :

  Euarchontoglires  
  Euarchonta  

 Pointed Squirrel (Scandentia)


  Primatomorpha  

 Giant Glider (Dermoptera)


   

 Primates (Primates)




 Glires 

 Hare-like (Lagomorpha)


   

 Rodents (Rodentia)




In addition, the monophyly of the giant gliders could also be genetically confirmed, as a special group of so-called short interspersed nuclear elements (SINEs) could only be detected in them. As a rule, for all members of the Euarchonta, these consist of sections that are tRNA homologous and further sections without equivalence to tRNA. The SINEs found in the giant gliders only contain tRNA-homologous sections and are accordingly referred to as tSINEs. So far, this structure of the SINE is unique in mammals.

Internal system

Philippines glider ( Cynocephalus volans )

The first scientific description of the giant gliders comes from Johann Karl Wilhelm Illiger from 1811. In his work Prodromus Systematis Mammalium et Avium , which was based on Wilhelm von Humboldt's royal natural collection , Illiger described a large number of new genera, consistently used a biological species concept and contributed significantly to the introduction of the family as a systematic rank . The two species, however, were described earlier by Carl von Linné ( Cynocephalus volans , 1758) and Jean Baptiste Audebert ( Galeopterus variegatus , 1799).

In the past, the two recent species were classified in a common genus, Cynocephalus . Due to morphological differences between the two species, especially in the structure of the teeth, which are designed for harder food in the Malaysian glider than in the Philippines glider, the scientific name Galeopterus variegatus can be found in the more recent literature for the Malaysian glider ( First description by Oldfield Thomas 1908), whereby the species are placed in two different genera.

Giant gliders and people

The giant gliders' way of life makes it difficult to count or estimate the population, but the Malaysian glider is more numerous than the Philippines glider. Both species are sometimes considered pests, as they settle in coconut plantations , among other things, as a crop follower and feed on the flowers of the coconut plants or the buds.

A high loss of population through hunting can be recorded especially for the Philippines glider, which is hunted because of its soft fur and meat, which is considered a delicacy in some places. The Malaysian glider is fought mainly because it causes damage in the plantations. This is usually easy because the animals often choose similar or the same routes every night. The Filipinos aim with long-range weapons, mostly bows and arrows, at the regularly used landing areas of the animals and fire at the moment of landing. The constant deforestation of rainforests in the Southeast Asian archipelagos is another threat. The IUCN nevertheless lists both species as not endangered ( least concern , status 2008). The establishment of nature reserves is to be regarded as the most effective protective measure for giant gliders.

The keeping of the animals has so far not been possible because, among other things, the food consisting of leaves, buds and flowers is difficult to obtain outside of their habitat. Most of the animals die of indigestion in the first few days of keeping. In Kuala Lumpur ( Malaysia ), the city's institute for medical research achieved the most successful keeping of giant gliders to date: three specimens could be kept for a time with a diet of bananas , papayas , mangoes , lettuce and leaves of wild passion flowers . With this diet, the last animal died after 15 weeks. It is very likely that there will be no possibility of keeping, observing or multiplying giant gliders in captivity in the foreseeable future.

References

literature

  • TS Kemp: The Origin & Evolution of Mammals . Oxford University Press, Oxford 2005, ISBN 0-19-850761-5 .
  • Erwin Kulzer: Dermoptera. Giant gliders, fluttering lemurs, colugos . In: W. Westheide and R. Rieger: Special Zoology. Part 2: vertebrates or skulls . Spektrum Akademischer Verlag, Munich 2004, pp. 574-575, ISBN 3-8274-0307-3 .
  • Kathy MacKinnon: giant glider . In: David W. Macdonald (ed.): The great encyclopedia of mammals . Könemann Verlag, Königswinter 2004, ISBN 3-8331-1006-6 , pp. 432-433. (German translation of the original edition from 2001)
  • Ronald M. Nowak: Walker's Mammals of the World . 2nd Edition. The Johns Hopkins University Press, Baltimore 1999, ISBN 0-8018-5789-9 , pp. 250-252.
  • Thomas Schultze-Westrum: The giant gliders. In: Bernhard Grzimek et al. (Ed.): Grzimeks animal life . Vol. 11. Mammals 2 . Kindler Verlag, Zurich 1969, pp. 80–82.
  • Don E. Wilson, DeeAnn M. Reeder (Eds.): Mammal Species of the World . 3. Edition. The Johns Hopkins University Press, Baltimore 2005, ISBN 0-8018-8221-4 .
  • Erich Thenius and Richard Kraft: Riesengleiter in: Bernhard Grzimek (Ed.): Grzimeks Enzyklopädie, Volume 1: Mammals , Kindler 1988, ISBN 3-463-42101-1 , pp. 634–639.
  • Boonsong Lekagul & Jeffrey A. McNeely: Mammals of Thailand , ISBN 974-86806-1-4 , p. 39.

Web links

Commons : Cynocephalus  - collection of images, videos and audio files

References and comments

  1. a b Don E. Wilson and Russell A. Mittermeier (Eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, ISBN 978-84-16728-08-4 , pp. 284-285
  2. Urania Tierreich, Verlag Harry Deutsch, Frankfurt / Main and Zurich, Bd. Mammals p. 66
  3. ^ Charles H. Wharton: Notes on the Life History of the Flying Lemur. Journal of Mammalogy , Vol. 31 (3) 1950; Pp. 269-273
  4. James Ferguson-Lees and David A. Christie: Raptors of the World Helm, London 2001, ISBN 0-7136-8026-1 , pp. 721-722.
  5. From: Kathy MacKinnon: Riesengleiter . In: David W. Macdonald (ed.): The great encyclopedia of mammals . Könemann Verlag, Königswinter 2004, ISBN 3-8331-1006-6 , p. 432. (German translation of the original edition from 2001)
  6. From: Bernhard Grzimek (Ed.): Grzimeks Enzyklopädie, Volume 1: Säugetiere , Kindler 1988, ISBN 3-463-42101-1 , p. 635.
  7. ^ Mary R. Dawson, Malcolm C. McKenna, K. Christopher Beard and J. Howard Hutchinson: An Early Eocene Plagiomenid Mammal from Ellesmere and Axel Heiberg Islands, Arctic Canada. Kaupia 3, 1993, pp. 179-192
  8. According to JD Pettigrew, BGM Jamieson, SK Robson, LS Hall, KI McAnally, HM Cooper: Phylogenetic relations between microbats, megabats and primates (Mammalia: Chiroptera and Primates). in Philosophical Transactions of the Royal Society of London: Biological series, Vol. 325, 1989; Pp. 489-559 and M. C. McKenna, S. K. Bell (Eds.): Classification of mammals; above the species level. Columbia University Press, New York, 1997.
  9. ^ Mammals: Second row: Krallenthiere. In: Brehm's animal life. Colored original edition, Vol. 2 1883; P. 220. Quoted from Volume 76 of the Digital Library, Directmedia Publishing 2004, ISBN 3-89853-476-6 .
  10. ^ Gerhard Storch: Placentalia (Eutheria), Placentalier, Placentatiere. In: W. Westheide and R. Rieger: Special Zoology. Part 2: vertebrates or skulls . Spektrum Akademischer Verlag, Munich 2004, ISBN 3-8274-0307-3 , pp. 501–502.
  11. Boonsong Lekagul & Jeffrey A. McNeely: Mammals of Thailand , p. 39, ISBN 974-86806-1-4 .
  12. Ulfur Arnason, Joseph A. Adegoke, Kristina Bodin, Erik W. Born, Yuzine B. Esa, Anette Gullberg, Maria Nilsson, Roger V. Short, Xiufeng Xu, Axel Janke: Mammalian mitogenomic relationships and the root of the eutherian tree. in: Proceedings of the National Academy of Sciences (PNAS) 99, 2002; Pp. 8151–8156 full text
  13. Jürgen Schmitz, Martina Ohme, Bambang Suryobroto, Hans Zischler: The Colugo ( Cynocephalus variegatus , Dermoptera): The Primates' Gliding Sister ?. in: Molecular Biology and Evolution 19, 2002; Pp. 2308-2312 full text
  14. Oliver Piskurek, Masato Nikaido, Boeadi, Minoru Baba, Norihiro Okada: Unique Mammalian tRNA-Derived Repetitive Elements in Dermopterans: The t-SINE Family and Its Retrotransposition Through Multiple Sources. Molecular Biology and Evolution 20 (10) 2003; Pp. 1659–1668 full text
  15. For example in Wilson & Reeder 2005
  16. cynocephalus volans in the endangered Red List species the IUCN 2012. Posted by: JC Gonzalez, C. Custodio and others, 2008. Accessed May 30, 2013.
  17. Galeopterus variegatus in the endangered Red List species the IUCN 2012. Posted by: Boeadi & R. Steinmetz, 2008. Accessed May 30, 2013.
This version was added to the list of articles worth reading on October 17, 2006 .