Bradypus variegatus
Brown-Throated Three-Toed Slothsloth_first_pic.jpg

Class: Mammalia
Order: Xenarthra
Family: Bradypodidae
Genus: Bradypus

Geographic Range & Abundance:
The brown-throated three-toed sloth can be found in three parts of the world: Mexico, parts of Central America such as: Costa Rica, El Salvador, Honduras, Nicaragua and Panama. They are also found in parts of South America such as: Argentina, Bolivia, Brazil, Paraguay and Panama. The climate of these areas have a constant warm temperature, allowing vegetation growth through out the year as well as precipitation and humidity to play a significant role in the algae growth, which serves as camouflage for the sloth from predators.[3] However, sadly due to deforestation, habitat fragmentation and the multiple violations commited by humans, such as poaching these animals for their meat, the population of Bradypus variegatus has significantly been threatened and declined.

Coloration & Morphology:
patch of fur indicating male sloth

The Bradypus variegatus' overall body pelage color is a grayish brown with a darker brown forehead and suborbital marking that surround the eye. [3] Coloration of fur between the female and male sloth is actually quite different. As learned at the sancturay one difference is that a male sloth has a speculum, which is a orange-yellow patch that typically has a dark brown-black horizontal stripe bisected down the middle of its back in between their shoulder blades. Also the fur located at this patch on the body of a male sloth will tend to be shorter in length, compared to the rest of their body. [4] In general, the texture of the Bradypus variegatus fur is thick and coarse, the strands flow in a longitudinal manner that typically forms the shape of a groove, allowing the growth of green algae, a camouflage technique. The direction of their fur is interesting for it appears in a ventral to dorsal manner, which is opposite to most other mammals. This special orientation allows the rain to runoff of their bodies, which becomes extremely important to animals living in areas that have the means to accumulate up to 10,920 mm of rain per year. Underneath this protective fur is yet another layer consisting of thinner strands providing insulation for these mammals, allowing their bodies to drop during the hours of nighttime in order to conserve energy. Also it is interestingly to have learned the sloth is capable of rotating its head more 90 degrees.

skeleton of three-toed sloth

While traveling through Costa Rica, headed to our next destination we arrived at the Aviarios Del Caribe Sloth Sanctuary of Costa Rica, which helped me better understand the morphology of the Bradypus variegatus . Upon one of the walls of this sanctuary was a wall called “The Wall of Learning”, which stated that the common ancestor of present-day sloths were huge, terrestrial herbivores, for instance armadillos or anteaters. Since there ancestors were almost certainly an insectivore, a hertiage that has left the sloth at somewhat of a disadvantage for life as a herbivore, which can be seen in their incompleted zygomatic arches that contain and anchor the jaw's chewing muscles. [1] Another adapation and probably the most conspicuous to the upper echelons of the rainforest is its feet. At the sloth center we learned that sloths do not have heels so they are incapable of standing in a upright position. Hence why a sloth is at its best when suspended upside down from a horizontal limb because when in this position they are capable of completing any task needed such as sleeping, feeding, breeding, walking and even whistling. Also it was interesting to learn at the sloth center that the last joints of the digits do the holding therefore the sloth is able to maintain a strong grip on objects even when the their wrist is being twisted and rotated almost 180 degrees! However, there is a consequence of the sloth's special foot structure, which is their dependence on thin supports, therefore they are unable to manage well on hefty, thick horizontal branches.
claw of three-toed sloth
Technically, sloths belong to two very distinct families, Megalonychidae (two-toed sloth) and Bradypodidae (three-toed sloth), unfortunately these two families are no longer closely related to each other. One difference resides in the number of vertebrae, a three-toed sloth has nine, which helps with flexibility, while a two-toed sloth has only six and therefore there range in movement is limited. Another difference is the two-toed sloth is visibly larger as well as nocturnal, while the three-toed sloth, although smaller will continuously remain active, daytime and nighttime. Another feature that can be noted as a difference between the Bradypus and Choloepus is the muzzle is darker and shorter in Choloepus, resembling more pig-like. [4] It is understood that the reason their ancestors spent much of their time in trees was to escape the predators on land, for this reason the Bradypus variegatus came to adapt their laid-back and unobtrusive lifestyle.
morphology of the sloth

The brown-throated three-toed sloth has the capability to be highly adaptive to their habitats, therefore locations tend to vary. They are most common habitats for these animals are rainforests and evergreen forests, but parks and pastures are other considered habitats.
Usually they can be found in between the canopy and understory layers of a tree. At times a sloth will spend up to three days in a single tree before deciding to move to another one.The structure of the tree is very crucial for the survival of these creatures. Since the bradypus variegatus are slow moving creatures that enjoy sleeping a good amount, they have to be able to rely on these trees to be structurally suitable for their needs.
The crowns of the trees tend to have thick interlocking lianas, which will provide the functional needs for these animals, such as mating, sleeping, eating and traveling. Sloths climb trees in a vertical manner, therefore trees need to be positioned close together in order for the sloth to move around the forest canopy.


Unfortunately, due to the sloths very slow movement these three-toed sloths become easy targets for their predators. One of their main predators is a bird known as the Harpy Eagle. Harpy Eagles are the heaviest eagles in the world and can weigh up to 7.5 kilograms, compared to the Brown-throated three-toed sloth weighing a measly 4 kilos. [1] Several different studies of harpy nests have found that the sloth constitutes the single lagest component of the harpy's diet. [1] Among other predators include jaguars and ocelot, caimans, large snakes such as the anaconda and humans. Sadly, in Costa Rica, this three-toed sloth at times experiences a slow death from either electrical lines or poachers. One way a sloth has learned to protect themselves from predators is by camouflaging,which is established from precipitation and humidity. Since their hairs have tiny grooves in which green algae can grow, they often tend to look like masses of dry vegetation. three-toed_sloth.jpgIn turn, this camouflage behavior serves as a symbiotic relationship between the sloth and snout moth, which forages on the algae growth.[3] The snout moth also known as Crambus agitatellus will not only feed off the sloth, but it will also lay its eggs in the feces of the sloth. However, its main defense against predators is a "claw and nip" motion with their sharp claws.
Crambus agitatellus;


Sloths have gained the reputation of being very tranquil animals, if they were to cross paths with a human they typically will not pay much attention to us and continue on their way, previously doing what they had set out to do before encountering us. As mentioned above their hands and feet have evolved into hooks like appendages allowing them to hang from the limbs of trees. Three-toed sloths are only active for an average of ten hours per day, therefore one can acknowledge that these animals are very good at conserving their energy. Due to their high-fiber diet sloths' have a low body temperature ranging from 86 to 93 degrees F (30 to 34 degrees C), therefore they conserve much of their energy by performing in the nightly task of hibernating. [1] During the night time a sloth will allow their body temperature to drop with the temperature at night, to be precise as much as 20+ degrees Celsius! [1] Once the sun rises in the morning and beams onto the treetops, the sloths will simply lie out and sunbathe so that their body temperature will rise to the required levels needed to resume their daily activities.
Sloths are considered to be canopy species, therefore it was very interesting to find out these animals have unique bathroom habits. Instead of simply dropping their feces from the canopy trees, they will make a weekly night trip down to the ground and dig a hole with their stubby tail to deposit their urine and droppings. During this weekly visit to the ground floor, a sloth is capable of losing up to one third of their body weight. Once the sloth finishes their bathroom business on the ground floor they cover up their hole and make their way back up to the canopy trees.

Reports have been made that typically Bradypus variegatus will mate before the beginning of a rainy season. In order to attract males, the female B.variegatus will use vocal signals. During the actual mating process the female will vocalize continuously for about fifteen minutes. Once mating has occurred between a male and female sloth, the male sloth will leave and the female will give birth five to six months later. Interestingly, one of the rare measurements of a new-born three-toed sloth revealed that its weight was only 5 percent that of an adult, in mammalian terms this is a significantly low figure. [1] Typically an adult female sloth will only give birth to one sloth, it is rare but there are cases of a sloth giving birth to twins. The baby sloth is generally carried on the stomach of its’ mother. The behavior of a mother sloth towards its offspring is interesting. For the first six weeks the offspring is nursed. Once the six weeks are over the baby sloth will have to learn to feed itself, they do this by grasping for food that are found in tress where the mother and baby sloth are living. Once the sloth reaches the age of six months, the sloth will leave one foot on its mother when reaching for food, then after about nine months the once baby sloth is left to live on its own. [1]
baby sloth

Three-toed sloth’s are folivores and their diet consist mostly of leaves, particularly from a specific tree called the
Cecropia Tree, which makes sense since these trees also serve as a home for these sloths. However, they will not only feed on this particular tree, there are up to thirty different tree species that are considered a food source for these animals, as well as the twigs of these trees. [4] Sloths have small molars used to chew up their leafy diets containing many calories that are not easily digested due to the toughness of the cellulose. Therefore, it is important the sloth has a huge, multichamered stomach that functions much like the digestive system of cows and othe ruminants, which will fill one-third of the sloth's body and is also rich in bacteia allowing the cellulose to be digested. [1] Leaves ingested by the sloth can spend up to an average of one month in the stomach before moving on to the small intestine. [1] Bradypus variegatus inherit their feeding habits from their mother during a "social weaning" process meaning the selection of tree choosen by the mother for a meal source will also be the tree favored by the baby sloth. [4] Their diet at times can also include insects as well as small lizards.The requirement of moisture for these animals are met from their leaf meals, therefore there is no need for them to seek out to find drinking water.
sloth eating cecropia fruit

Interactions With Other Species:

Negative Interactions
As stated above, the harpy eagle and jaguar are the two main predators for the three-toed sloth. Humans will also poach sloth for its meat.
Positive Interactions:
Symbiotic relationship with the snout moth. (Algae develops in tiny grooves of three-toed sloth and the snout moth will feed on the algae)

baby sloth covered in manage medication

Personal Experience:

Unfortunately, I did not see the three-toed sloth at La Selva in its natural habitat. Instead during our four day visit in La Selva we saw the two-toed sloth, which was nice to observe in its habitat. However, I was able to see the three-toed sloth when we stopped and visited the Sloth Sanctuary on our journey to Cahuita. The majority were babies, but i did find out a very interesting fact while there, which was the baby sloths are covered in mange medication, which is a combination of coconut oil and a natural flower extract called chochay and then both of these contents are mixed in a blender, which will turn the sloths a red color.


Works Cited
[1] Forsyth, Adrian. Nature of the Rainforest: Costa Rica and beyond. San José: Zona Tropical Publication, 2008. Print.
[2 ]"Sloth at Animal Corner." Animals, Farm Animals, Wildlife Animals, Pets at Animal Corner. Web. 14 Mar. 2010. <>.
[3] "Species Account for Bradypus Variegatus, Brown-Throated, Three-ToedSloth." University of Wisconsin-Stevens Point. Web. 14 Mar. 2010. <>.
[4] "Three-Toed Tree Sloths (Bradypodidae)." Novelguide: Free Study Guides, Free Book Summaries, Free Book Notes, & More. Web. 19 Apr. 2010. <>.