Sloths:
A look at the sloths from Costa Rica and other various sloth essentials
Most people are familiar with the word sloth in terms of laziness. This term comes from a resident of the neotropics, the sloth, due to its slow movement. The sloth usually moves less then 125 feet per day (Sloth, 2001). A possible explanation for its slowness is that the sloth comes from the order Edentata. A characteristic of animals from the order of Edentata, which helps contribute to the sloth to be slothful, is a low metabolic rate and body temperature; the slothÕs body temperature is around 91 degrees F (Sloth, 2001).
There are two families of sloths. Two toed sloths (2 species) belong to family Megalonychidae, genus Choloepus and the three-toed sloth (3 species) fall in to family Bradypodidae, genus Bradypus (Enchanted, 2001; Reid, 1997). The two families of sloths are only distantly related. The two-toed sloth is of the same family of the extinct giant ground sloth. Regardless of what family the sloths come from, they share many similar features such as being arboreal (Emmons, 1997).
General Sloth Characteristics
Long limbs, short bodies and a very short or no tail are characteristic of the sloth. Long, curved claws enable the sloth to hang upside down from trees without using their muscles. This helps them to use less energy (Reid, 1997). The sloth will climb tree branches hanging upside down and in a hand over hand manner. Since they spend most of their life inverted, their shaggy fur is arranged to lay flat from the belly to the back of the head (Emmons, 1997). In addition, the liver, stomach, spleen and pancreas are in different positions due to the sloth spending most of its life upside down (Parker, 1990).
The sloth will spend 15 hours a day sleeping and will only wake to eat or move. They have a long digestive period and are well adapted to gain all they need from a low energy diet of leaves and other vegetation (Reid, 1997). The vegetation is fermented by bacteria in a multi-chambered stomach (Emmons, 1997). If bothered while snacking on leaves, the sloth hides from predators by curling up into a tight ball to look like a nest or a tree growth (Reid, 1997).
Types of Sloths
The five species of sloths are as follows: brown-throated three-toed sloth (Bradypus variegates), pale-throated three-toed sloth (Bradypus tridactylus), maned three-toed sloth (Bradypus torquatus), HoffmannÕs two-toed sloth (Choloepus hoffmanni), and southern two-toed sloth (Choloepus didactylus). HoffmannÕs two-toed sloth and brown-throated three-toed sloth, representing both families, are found in Central America (Reid, 1997). The brown-throated three toed-sloth habitat is lowland evergreen and deciduous forest as well as second growth areas, but is at times found in highland forests. The HoffmannÕs two-toed slothÕs habitat is evergreen and semi deciduous forest, and second growth lowlands and highlands areas. Both are rarely found in dry, lowland forests (Reid, 1997). The following text takes a closer look at the two sloths found in Costa Rica and some other sloth particulars.
Brown-throated three-toed sloth
The brown-throated three-toed sloth is less than 2 feet long, weighs 7.7-9.4 lbs and is known for its ŌsmilingĶ face (Sloth, 2001). There are other distinguishing characteristics such as the coarse and wavy fur is brownish-gray with the throat and chest area being brown. The tail is short like a stump, ~2 inches. There are three claws on each stocky foot (furry foot pad) and the front legs are much longer then the hind legs. The nose is black and the eye is outlined in black, which then extends as a stripe to the ear. The ears are not easily seen and the head is small and round. On males, in between the shoulder blades, there is a large path of short orange fur with a brown stripe (Emmons, 1997). This animal can turn its head in a 270-degree arc due to nine neck vertebrate (Britannica, 1999).
Unlike the HoffmannÕs, the brown-throated is both nocturnal and diurnal, but is a bit more active during the night (Emmons, 1997). They will often let their body temperature drop at night, but will soak up the sun during the day in order to increase their body temperature. A good portion of the day will be spent on a branch or in vines and sometimes curled in a ball between two tree branches (Reid, 1997).
About once a week the brown-throated will take an hour to descend to the ground in order to defecate. Holding onto the tree truck they will dig a hole with their tail, defecate and then cover it (Emmons, 1997). This takes about thirty minutes. There are a few theories about why the sloth does this. One is that by defecating at the base of the tree, the nutrients will return to the tree to grow more leaves. The other is that predators cannot find the sloth by following its scent from the scat (Kricher, 1997).
If the brown-throated sloth is on the ground it is a very weak walker. It basically drags itself. On the other hand they are excellent Ōtree walkersĶ and are also good swimmers (Emmons, 1997). When on the ground it is easy prey for ocelots, large snakes, jaguars, harpy eagles, and people (Enchanted, 2001). The brown-throat is relativity docile, so remaining camouflaged in the trees is itÕs best defense against predators. The only noise it makes is a rare shrill whistle (Emmons, 1997).
It was thought that the brown-throated only ate leaves from the Cecropia tree. In reality they eat at least 96 other types of leaves (Kricher, 1997). The reason it was thought that the brown-throated only ate Cecropia leaves is because in those trees the brown-throated sloth was easily spotted. Young leaves of any tree are preferred because they are easier to digest (Reid, 1997). After about a day and a half the brown-throated will move to a new tree to find more leaves (Kricher, 1997). Their range is about 1.6 hectares with 5 to 8 found per hectare. Even though their range may over lap with other sloths, they are solitary animals and will rarely feed from the same tree (Reid, 1997). Their life span is 20 to 30 years (Reid, 1997).
HoffmannÕs two-toed sloth
HoffmannÕs two-toed sloth is a little more than two feet long and weights between 8.8-17.6 lbs (Sloth, 2001). Its snout-like face has large, widely spaced nostrils; contains large, brown eyes; and is covered by white fur. The long, coarse fur is a dull cream-brown with the legs being a dull red-brown. The tail is basically non-existent. The front legs are a touch longer than the back legs. Fur is absent on the pads of its long narrow feet and there are 2 claws on the front feet and 3 claws on the hind feet (Reid, 1997). The young are dark brown with short coarse fur (Emmons, 1997). The HoffmannÕs has six or seven vertebrae and has less range of motion of their head as compared to the brown-throated sloth (Parker, 1990).
The HoffmannÕs is nocturnal, but on occasion may move to a new position to feed during the day. They are better able to maintain their body temperature, but still seek out sunny treetops (Reid, 1997). The HoffmannÕs is less numerous than the brown-throated, but they can be readily found in pastures with a few trees or descending liana vines at night. Approximately once a week they descend to defecate, but they do not dig a hole (Emmons, 1997). They are slightly better than the brown-throated at walking, but it is still an awkward event, swimming is a better choice (Reid, 1997).
The HoffmannÕs sloth is faster and more aggressive than the brown-throated sloth, which helps if threatened. Jaguars, ocelots, large snakes, harpy eagles, and humans are the main threat to the HoffmannÕs as well (Enchanted, 2001). If disturbed, they will defend themselves by lashing out with their claws or biting. They are much happier if left to eating leaves, flowers, twigs, and fruit. At times they will chew on tree trunks to feed off of the lichen and moss (Reid, 1997). An interesting note, the HoffmannÕ sloth will eat meat when in captivity (Meritt, 1985).
Sloth Fur
The sloth has a very unique characteristic, its fur. As mentioned earlier, the fur slopes from the belly to the back. It is thought this helps rain to run-off. The thickness of the fur and skin provides a sort of armor against ants and possible predators (Goffart, 1971). Each hair is pitted or grooved which makes for a place to grow algae. This makes the sloth appear greenish, which makes a very handy camouflage in the canopy (Reid, 1997). It is thought that by licking or absorbing the algae through their skin, sloths maybe gaining nutrients (Sloth, 2001). An algae culture from a brown-throated sloth showed four phyla. The algae can be found on sloths that are a few weeks old (Aiello, 1985).
The sloth may rarely hang out (heh, heh) with other sloths, but they are far from alone. Within their fur a tiny moth lives. These moths will lay eggs in the slothsÕ dropping and when they hatch the larva feeds on the scat (Kricher, 1997). Sloths are also home to ticks, lice, and caterpillars of a certain Pyralididae spp (Goffart, 1971).
Sloth Reproduction
It is not entirely clear how the female and male attracts each other. The thought is that the male finds the female when she, Ōemits loud bird-like eee or a-eee cries at regular intervalsĶ (Goffart, 1971). Like everything thing else in a sloths life copulation occurs in the trees, but a few have witnessed the sloths mating on the ground. In some sources it was said that sloths mate year round (Sloth Home, 2001) and in others the mating season was listed as March or April, before the wet season (Goffart, 1971).
The gestation period lasts 4 to 6 months and birth occurs in the trees. The baby is about 10 inches and 12 oz at birth and will hold onto its motherÕs chest for the first 5 weeks (nice hammock!) (Parker, 1990). At about five weeks the sloth is weaned and starts to take leaves from its mother. The sloth will stay with its mother for over six months and may continue to be nursed for 1 to 2 years (Goffart, 1971).
The young sloths are faster movers then their parents. Their eyesight is also better (the parents eyesight is not very good). As the sloth becomes older they will lose some of their eyesight and start to depend on their keen sense of smell (Goffart, 1971).
Threatened?
The only sloth that is currently endangered is the Maned sloth, which is found in the Brazilian rainforest (Sloth Home, 2001). This is due to habitat loss from deforestation. All of the other sloths are not threatened or endangered at this time. One cannot be entirely sure of this because the sloth is a hard to find creature. Many sloths are over looked due to their camouflage and slow movement (Reid, 1997).
They seem to be better at handling habitat stresses than other animals, but that is not to say they will thrive like the Norway rat or pigeons around humans. There are currently several forest reserves, such as Manuel Antonio and Tortuguero National Parks in Costa Rica, which are home to the HoffmannÕs and brown-throated sloths (Reid, 1997).
Works Cited
Aiello, A. ŌSloth Hair: Unanswered Questions.Ķ The Evolution and Ecology of
Armadillos, Sloths, and Vermilinguas. Washington: Smithsonian Institution
Press, 1985.
Britannica.com. Encyclopedia Britannica: Sloth. 1999. Available from the Internet,
http://britannica.com/bcom/eb/article/9/0,5716,69989+1,00.html, accessed 20
March 2001.
Emmons, Louise H. Neotropical Rainforest Mammals. Chicago: The University of
Chicago Press, 1997.
Enchanted Learning Software. All About Sloths. 2001. Available from the Internet,
http://www.enchantedlearning.com/subjects/mammals/sloth/, accessed 8 May
2001.
Goffart, M. Function and Form in the Sloth. New York: Pergamon Press, 1971.
Kricher, John. A Neotropical Companion. Princeton, NJ: Princeton University Press,
1997.
Meritt Jr., D.A. ŌThe Two-toed HoffmanÕs Sloth, Choloepus hoffmanni Peters.Ķ The
Evolution and Ecology of Armadillos, Sloths, and Vermilinguas. Washington:
Smithsonian Institution Press, 1985.
Parker, Sybil, ed. GrzimekÕs Encyclopedia of Mammals, Vol 2. McGraw-Hill Publishing
Company, 1990.
Reid, Fiona A. A Field Guide to the Mammals of Central America and Southeast Mexico.
New York: Oxford University Press, 1997.
Sloth the Mammal and Its Habitat. 2001. Available from the Internet,
http://www.geocitites.com/EnchantedForest/Dell/5094/SlothMammal.html,
accessed 20 March, 2001.
Sloth Home. Sloth Home. 2001. Available from the Internet,
http://www.sloth.4t.com/Info/info.html, accessed 8 May 2001.
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