Actual two-toed sloth

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Actual two-toed sloth
Actual two-toed sloth (Choloepus didactylus)

Actual two- toed sloth ( Choloepus didactylus )

Systematics
Order : Tooth arms (pilosa)
Subordination : Sloths (folivora)
Superfamily : Mylodontoidea
Family : Choloepodidae
Genre : Two-toed sloth ( Choloepus )
Type : Actual two-toed sloth
Scientific name
Choloepus didactylus
( Linnaeus , 1758)

The actual two- toed sloth or Unau ( Choloepus didactylus ) - sometimes just called the two-toed sloth - is a species from the Megalonychidae family . It is common in northern South America and inhabits tropical rainforests . There it lives mostly solitary in the treetops, with a head-hanging position being typical, and feeds on leaves, but rarely also on animal food. The way of life of wild animals has only been insufficiently researched. Characteristic are the long limbs and the brown hair color, whereby the coat consists of only one layer, the outer hair. The population of the sloth is not considered to be threatened.

description

Habitus

Actual two-toed sloth

The actual two-toed sloth reaches a head-trunk length of 54 to 88 cm, the extremely short and hardly movable tail is between 0.9 and 2 cm long. The weight varies from 6.5 to 11.8 kg. This makes the real two-toed sloth slightly larger than its relative, the Hoffmann's two-toed sloth ( Choloepus hoffmanni ). The differences between the sexes are only slight, so the females are slightly larger than the males. The head is generally small, but longer in contrast to the three-toed sloth . It generally has a rounded profile. The ears are small, around 2.8 cm long and not externally visible. The fur has only a single layer, the top coat with hair up to 17 cm long. It is usually gray-brown in color, with the belly side often appearing lighter than the back side. The face is light brown and hairless and has a leathery texture. Depending on the incidence of light, especially in the rainy season , the fur shimmers slightly green. This goes back to a symbiosis with algae that live in the fur, whereby this symbiosis is partly used to camouflage from predators. The vertex of the fur does not lie on its back as in other mammals, but on its stomach as in other sloths. This ensures that the rainwater can drain off better. The limbs are extremely long and end in two rays at the front and three at the back. These are about the same length and have long, curved claws. The rear foot length is up to 14.8 cm.

Skull and dentition features

The skull becomes between 10 and 17 cm long. At the cheekbones the width is 7.3 cm, but only 3.6 cm behind the eyes. The zygomatic arch is not fully developed. At the anterior attachment, however, it has an additional bone process pointing downwards. As with all sloths, the dentition differs from that typical of mammals . Each branch of the jaw has five teeth at the top and four at the bottom, a total of 18. The posterior ones appear molar-like , the foremost is conically pointed and thus resembles the canine tooth , and is separated from the posterior teeth by a larger diastema . It clearly towers above the rear teeth. Incisors are not developed. The upper row of teeth reaches a length of 4.5 cm.

Sensory performances and vocalizations

The two- toed sloth's sense of sight is poorly developed and only designed for short distances of up to 4 m. Only a few vocalizations are known. Cubs call their mother when they are separated from each other. The sounds emitted reach low frequencies of around 1.4 kHz. So far, only a hissing has been documented in adult animals.

distribution

Distribution area of ​​the actual two-toed sloth

The distribution area of ​​the actual two-toed sloth includes northern South America from Colombia , eastern Ecuador and Peru via Venezuela south of the Orinoco , Guiana , Suriname and French Guiana to Brazil north of the Amazon . The southernmost distribution limit in the western Amazon is not fully understood, occasionally sightings of the actual two-toed armadillo also take place far south of the Amazon. Especially in the western Amazon there is some overlap with the distribution area of ​​the Hoffmann two-toed sloth. The species is most frequently found in the humid tropical rainforests of the lowlands of the Amazon basin , but it also occurs up to heights of 2438 m. The habitat is characterized by high precipitation of more than 2000 mm annually and short dry seasons. The entire distribution area is given as around 4.2 million square kilometers. The population density fluctuates. On the Sinnamary River in French Guiana, it is around 0.9 individuals per square kilometer, but it can also rise to 4.5. In the region around Manaus it is 0.13 individuals per hectare and at Mamirauá in the Brazilian state of Amazonas it increases to 0.88 individuals on a comparable area size.

Way of life

Territorial behavior

Actual two-toed sloth in the branches

The way of life of the real two-toed sloth has not been adequately researched; most data are based on observations on animals in captivity and not on wild animals. It is crepuscular and nocturnal and lives solitary, social communities are only known between mother and young animal. Occasionally, aggressive behavior has been observed between males that can be fatal. Both the sharp claws and the canine-like front teeth are used. The sloth species spends almost its entire life in the treetops of the rainforest, around 24 to 30 m above the ground. The real two-toed sloth clings to branches with its strongly curved claws, a position that may reduce balance problems with swinging branches and save energy. When resting, it lies with its lower back on a branch and holds one to three limbs. The rest phase takes up almost 75% of the duration of the day, more than half of which is spent sleeping. The rest of the activity consists of eating and grooming. The movements are generally slow, only around 0.5 to 0.6 km per hour and a maximum of 1.6 km per hour. The treetops are usually only left to change location, but this is often done via the branches or with the help of hanging lianas . On the ground, the sloth species is rather clumsy and moves there on the elbows and forearms. Due to the low metabolism , the real two-toed sloth only needs to defecate every 3.4 to 4.6 days, which occurs on the ground or near the base of the trunk. It climbs down the trunk with its head down. Unlike the three-toed sloth, the droppings are not buried. This so often collects as a small hill around the tree.

food

Little is known about the diet of the actual two-toed sloth in the wild due to its nocturnal lifestyle. But like its relative, the Hoffmann two-toed sloth, it is a predominant herbivore. In addition to leaves , fruits , legumes , buds and flowers , insects , eggs , nestlings and small vertebrates are also part of the menu. Overall, the range of food consumed by the Hoffmann two-toed sloth is much more diverse than that of the three-toed sloth, which can also be assumed for the actual two-toed sloth. In captivity, an animal consumes around 350 g per day. Occasionally, single individuals have been observed at human latrines. This may be used to supplement the diet with important nutrients like proteins or minerals like salt .

Reproduction

The reproduction of the common two-toed sloth has been little researched. The females become sexually mature at around three years of age, the males only at around four and a half years. The mating season is year-round, with oestrus occurring every 32 days. After a gestation period of ten months, the female gives birth to a young and the birth takes about 35 minutes. The birth weight is around 360 g with a total length of 21 to 25 cm. The newborn has open eyes and a slightly darker coat than adult animals. It is partially able to climb and independently climbs the mother's belly ( fleeing nest ). The young animal spends the first nine to ten months of life on the mother's belly, which protects the young very actively. The young animal begins to eat solid food as early as four to five weeks, the proportion of which increases gradually. After three to five months, when the young has reached about 15% of the weight of an adult animal, weaning takes place. The animals are fully grown at the age of two and a half. The interval between two births is 16 months. Little is known about the life expectancy of the actual two-toed sloth in the wild. Animals in captivity were sometimes over 25 years old, the highest documented age is around 50 years.

Predators and enemy behavior

The most important predators include the South American coati , the jaguar , the long-tailed cat and occasionally the ocelot , as well as anacondas . Among the birds, the harpy should be highlighted. The greatest danger of falling prey to predators is when the two-toed sloth descends from the tree.

Parasites and commensals

Due to the lack of an undercoat, external parasites are not as common in the two-toed sloths as they are in the three-toed sloths. The typical ones that attack the two-toed sloth are mainly ticks of the genus Amblyomma , as well as bugs such as Clerada , mites such as Edentalges and various mosquitoes . Lice such as Lymeon have also been found in the fur. The parasites do not include moths of the genus Cryptoses , which also colonize the fur. These lay eggs in the manure of the two-toed sloth and release nitrogen compounds to the algae that live in the fur. By licking the fur, an animal also absorbs the algae and receives important supplements that are not provided by the rather low-energy food.

Among the internal parasites mainly include roundworms , here are Bostrichodera , Dioctophyme and Diptetalonema important. Furthermore, protozoa such as Endotrypanum and Leishmania as well as the single-celled Trypanosoma and Eimeria could be detected.

Systematics

Internal systematics of recent sloths according to Delsuc et al. 2004
  Pilosa  

 Vermilingua (anteaters) 


  Folivora (sloths)  
  Choloepodidae  

 Choloepus (two-toed sloth)


  Bradypodidae  

 Bradypus (three-toed sloth)




Template: Klade / Maintenance / Style
Historical representation of the actual two-toed sloth from 1902

The actual two -toed sloth is one of two species from the genus of the two-toed sloth ( Choloepus ). The position of the two-toed sloth within the subordination of the sloth (Folivora) is assessed differently. According to skeletal anatomical characteristics, most scientists favor an assignment to the Megalonychidae family . However, according to molecular genetic studies and protein analyzes from 2019, this is polyphyletic and includes both large ground sloths from South and North America and the forms of the West Indies . The individual groups are not closely related to one another. The investigations therefore advocate classifying the two-toed sloths in the monotypical family of the Choloepodidae , which in turn belongs to the superfamily of the Mylodontoidea . The next related group within the recent sloths are the three-toed sloths ( Bradypus ), which represent their own, likewise monotypical family. The sloths are combined with the anteaters (Vermilingua) in the closer family group of the tooth arms (Pilosa), an order within the secondary articulated animals (Xenarthra). Molecular genetic studies have shown that sloths split off from their common lineage with anteaters in the late Paleocene , around 58 million years ago. The two genera Bradypus and Choloepus , which are still alive today , separated from each other in the Oligocene around 29 million years ago. The lines that led to the two current species of two-toed sloths split in the Upper Miocene about 9 million years ago.

There are no known subspecies of the two-toed sloth. However, the western and eastern populations are different from each other. Should the actual two-toed sloths of Colombia and Ecuador receive a status as an independent subspecies, three possible names are available according to the rules of the ICZN . C. d. columbianus , C. d. florenciae and C. d. napensis . The former would have priority since it was first introduced by John Edward Gray in 1871. One of Einar Lönnberg's 1928 originally named C. d. pallescens introduced subspecies from Peru is now considered to belong to the Hoffmann two-toed sloth ( Choloepus hoffmanni ). Fossil finds of the real two-toed sloth are not known.

The first description of the actual two-toed sloth was in 1758 by Linnaeus . At that time, however, he classified the sloth species as Bradypus didactylus together with the white-throated sloth ( Bradypus idactylus ) in the genus of the three-toed sloth ( Bradypus ) and differentiated the two species based on the number of fingers on the forefeet. He gave Zeylona (today's Sri Lanka ) as the type locality, and it was not until 1911 that Oldfield Thomas established Suriname as the actual type locality. Johann Karl Wilhelm Illiger introduced the genus name Choloepus in 1811 and included the genus with the two-toed sloth as a species. The species name didactylus refers to the reduced number of toes on the front feet.

Danger

Actual two-toed sloth in the Duisburg Zoo

There are no known major threats to the population of the two-toed sloth. It is rarely sighted and hunted due to the way of life high in the trees and the slow movements. In French Guiana , hunting for food is permitted, but all trade is prohibited. Some indigenous peoples consider the meat of the sloth species taboo . Local populations can be affected by the destruction of the rainforest. Due to its large distribution area, the two-toed sloth is not considered endangered, the IUCN lists it as “not endangered” ( least concern ). The sloth species is present in numerous protected areas, including the Saracá Taquera National Forest in the Brazilian state of Pará . In addition, it is kept relatively often in zoological institutions.

literature

  • Peter J. Adam: Choloepus didactyla. Mammalian Species 621, 1999, pp. 1-8
  • Nadia Moraes-Barros: Megalonychidae (Two-toed sloths). In: 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, pp. 104–117 (p. 117) ISBN 978-84-16728-08-4
  • Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9

Individual evidence

  1. ↑ C. Richard-Hansen, J.-C. Vié, N. Vidal and J. Kéravec: Body measurements on 40 species of mammals from French Guiana. Journal of Zoology (London) 247, 1999, pp. 419-428
  2. ↑ a b DP Gilmore, CP Da Costa and DPF Duarte: Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses. Brazilian Journal of Medical and Biological Research 34 (1), 2001, pp. 9-25 ( [1] )
  3. ↑ a b c d e f g h i j k l m Peter J. Adam: Choloepus didactyla. Mammalian Species 621, 1999, pp. 1-8
  4. ^ A b Robert S. Voss, Darrin P. Lunde and Nancy B. Simmons: The mammals of Paracou, French Guiana: A beotropical lowland rainforest fauna part 2. Nonvolant Species. Bulletin of the American Museum of Natural History 263, 2001, pp. 3–236 (pp. 64–65)
  5. ↑ a b c d e Nadia Moraes-Barros: Megalonychidae (Two-toed sloths). In: 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, pp. 104–117 (p. 117) ISBN 978-84-16728-08-4
  6. ↑ Cristiano Trapé Trinca, Francesca Belem Lopes Palmeira and José de Sousa e Silva Júnior: A Southern Extension of the Geographic Distribution of the Two-Toed Sloth, Choloepus didactylus (Xenarthra, Megalonychidae). Edentata 7, 2006, pp. 7-9
  7. ↑ a b Tinka Plese and Adriano G. Chiarello: Choloepus didactylus. Edentata 11 (2), 2010, p. 127
  8. ↑ Erica Taube, Jean-Christophe Vié, Pascal Fournier and Christophe Genty: Distribution of Two Sympatric Species of Sloths (Choloepus didactylus and Bradypus tridacfylus) along the Sinnamary River, French Guiana. Biotropica 31 (4), 1999, pp. 686-691
  9. ^ A b Adriano Garcia Chiarello: Sloth ecology. An overview of field studies. In: Sergio F. Vizcaíno and WJ Loughry (eds.): The Biology of the Xenarthra. University Press of Florida, 2008, pp. 269-280
  10. ^ Virginia L. Naples: Form and Function of the Masticatory Musculature in the Tree Sloths, Bradypus and Choloepus. Journal of Morphology 183, 1985, pp. 25-50
  11. ↑ S. Troll, J. Gottschalk, J. Seeburger, E. Ziemssen, M. Häfner, J. Thielebein and A. Einspanier: Characterization of the ovarian cycle in the two-toed sloths (Choloepus didactylus): An innovative, reliable, and noninvasive method using fecal hormone analyzes. Theriology 80, 2013, pp. 275-283
  12. ↑ DER SPIEGEL: Mourning the world's oldest sloth Paula: The end of comfort. ( online ), accessed on August 10, 2020
  13. ↑ Erica Taube, Joël Keravec, Jean-Christophe Vié and Jean-Marc Duplantier: Reproductive biology and postnatal development in sloths, Bradypus and Choloepus: review with original data from the field (French Guiana) and from captivity. Mammal Review 31 (3), 2001, pp. 173-188
  14. ↑ Miguel Delibes, Javier Calzada, Cuauhtémoc Chávez, Eloy Revilla, Beatriz A. Ribeiro, Denise Prado, Claudia Keller and Francisco Palomares: Unusual observation of an ocelot (Leopardus pardalis) eating an adult Linnaeus's two-toed sloth (Choloepus didactylus). Mammalian Biology 76, 2011, pp. 240-241
  15. ↑ Mauro Galetti and Oswaldo de Carvalho Jr .: Sloths in the Diet of a Harpy Eagle Nestling in Eastern Amazon. The Wilson Bulletin 112 (4), 2000, pp. 535-536
  16. ↑ Jonathan N. Pauli, Jorge E. Mendoza, Shawn A. Steffan, Cayelan C. Carey, Paul J. Weimer and M. Zachariah Peery: A syndrome of mutualism reinforces the lifestyle of a sloth. Proceedings of the Royal Society B 281, 2014, p. 20133006, doi: 10.1098 / rspb.2013.3006
  17. ↑ Karen D. Sibaja-Morales, Jaqueline B. de Oliveira, Ana E. Jiménez Rocha, Jorge Hernández Gamboa, Jorge Prendas Gamboa, Francisco Arroyo Murillo, Janet Sandí, Yessenia Nuñez and Mario Baldi: Gastrointestinal Parasites and Ectoparasites of Bradypus variegatus and Choloepus Hoffmanni Sloths in Captivity from Costa Rica. Journal of Zoo and Wildlife Medicine 40 (1), 2009, pp. 86-90
  18. ↑ a b Frédéric Delsuc, Sergio F Vizcaíno and Emmanuel JP Douzery: Influence of Tertiary paleoenvironmental changes on the diversification of South American mammals: a relaxed molecular clock study within xenarthrans. BMC Evolutionary Biology 4 (11), 2004, pp. 1-13
  19. ↑ Robert P. Anderson and Charles O. Handley, Jr: A new species of three-toed sloth (Mammalia: Xenarthra) from Panamá, with a review of the genus Bradypus. Proceedings of the Biological Society of Washington 114, 2001, pp. 1-33
  20. ↑ Timothy J. Gaudin: Phylogenetic relationships among sloths (Mammalia, Xenarthra, Tardigrada): the craniodental evidence. Zoological Journal of the Linnean Society 140, 2004, pp. 255-305
  21. ↑ Luciano Varela, P. Sebastián Tambusso, H. Gregory McDonald and Richard A. Fariña: Phylogeny, Macroevolutionary Trends and Historical Biogeography of Sloths: Insights From a Bayesian Morphological Clock Analysis. Systematic Biology 68 (2), 2019, pp. 204-218
  22. ↑ Frédéric Delsuc, Melanie Kuch, Gillian C. Gibb, Emil Karpinski, Dirk Hackenberger, Paul Szpak, Jorge G. Martínez, Jim I. Mead, H. Gregory McDonald, Ross DE MacPhee, Guillaume Billet, Lionel Hautier and Hendrik N. Poinar : Ancient mitogenomes reveal the evolutionary history and biogeography of sloths. 'Current Biology 29 (12), 2019, pp. 2031-2042, doi: 10.1016 / j.cub.2019.05.043
  23. ↑ Samantha Presslee, Graham J. Slater, François Pujos, Analía M. Forasiepi, Roman Fischer, Kelly Molloy, Meaghan Mackie, Jesper V. Olsen, Alejandro Kramarz, Matías Taglioretti, Fernando Scaglia, Maximiliano Lezcano, José Luis Lanata, John Southon, Robert Feranec, Jonathan Bloch, Adam Hajduk, Fabiana M. Martin, Rodolfo Salas Gismondi, Marcelo Reguero, Christian de Muizon, Alex Greenwood, Brian T. Chait, Kirsty Penkman, Matthew Collins and Ross DE MacPhee: Palaeoproteomics resolves sloth relationships. Nature Ecology & Evolution 3, 2019, pp. 1121-1130, doi: 10.1038 / s41559-019-0909-z
  24. ↑ Gillian C. Gibb, Fabien L. Condamine, Melanie Kuch, Jacob Enk, Nadia Moraes-Barros, Mariella Superina, Hendrik N. Poinar and Frédéric Delsuc: Shotgun Mitogenomics Provides a Reference Phylogenetic Framework and Timescale for Living Xenarthrans. Molecular Biology and Evolution 33 (3), 2015, pp. 621-642
  25. ↑ Manuel Ruiz-García, Diego Chacón, Tinka Plese, Ingrid Schuler and Joseph Mark Shostell: Mitogenomics phylogenetic relationships of the current sloth's genera and species (Bradypodidae and Megalonychidae). Mitochondrial DNA Part A 29 (2), 2018, pp. 281-299, doi: 10.1080 / 24701394.2016.1275602
  26. ^ A b Alfred L. Gardner and Virginia L. Naples: Family Megalonychidae P. Gervais, 1855. In: Alfred L. Gardner (Ed.): Mammals of South America, Volume 1: Marsupials, Xenarthrans, Shrews, and Bats. University of Chicago Press, 2008, pp. 165-168 ISBN 0-226-28240-6 , 9780226282404
  27. ↑ Oldfield Thomas: The mammals of the tenth edition of Linnaeus; an attempt to fix the types of the genera and the exact bases and localities of the species. Proceedings of the Zoological Society of London 1911, pp. 120-158
  28. ↑ FrançoisCatzeflis and Benoit deThoisy: Xenarthrans in French Guiana: a letter overview of Their distribution and conservation status. Edenata 13, 2012, pp. 29-37
  29. ↑ Sergio Moreno and Tinka Plese: The Illegal Traffic in Sloths and Threats to Their Survival in Colombia. Edentata 7, 2006, pp. 10-18
  30. ↑ Tinka Plese and Adriano G. Chiarello: Choloepus didactylus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. ( [2] ); last accessed on March 8, 2014
  31. ↑ Leonardo de Carvalho Oliveira, Sylvia Miscow Mendel, Diogo Loretto, José de Sousa e Silva Júnior and Geraldo Wilson Fernandes: Edentates of the Saracá-Taquera National Forest, Pará, Brazil. Edentata 7, 2006, pp. 3-7

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