How Sweet to be a Sloth

Common Name:
Two-Toed Sloth
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Two-Toed Sloth near La Selva


Latin Name: Choloepus didactylus

Family: Megalonychidae

Classification:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Pilosa
Family: Megalonychidae
Genus: Choloepus
Species: didactylus

Range and Abundance:
C. didactylus can be found in the tropical forest canopies of Central America and northern South America, including portions of Brazil and Peru. Specifically they are
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Map of the Range of the Two-Toed Sloth
found from the delta of the Orinoco River west to the upper drainage of this river in Columbia, east through French Guiana and in Brazil to the State of Maranhao.
Although sloths are not considered endangered right now, they are threatened by the loss of their rain forest habitat to natural and human deforestation


Coloration and Morphology:
The coloration of C. didactylus ranges from tan to "buffy brown". In the wild they may take on a greenish tint due to a green algae that lives on its hair. This algae helps them blend in to their surroundings, which allows them to avoid predation. The hair on the ventral side of the sloth is generally lighter than that of the back. They have long hair that is parted down the ventral midline and it is directed dorsally. This dorsal projection of hair is said to help water runoff the animal while it hangs upside down in its usual position. It has a light brown leathery face that lacks any fur.

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Wet Sloth - Notice the Two-Toes Grasping the Branch
The digits of all four feet are
syndactylous and C. didactylus
have a large curved claw,
important for hanging from the
branches in their habitat. These
features of their hands and feet
are adaptations for suspensory
locomotion, in addition to the
increased enhanced muscles in
their limbs.
Typically these two-toed sloths
are around 68 plus or minus 5cm
in length. Sexual dimorphism is not marked. C. didactylus young are born head first with their eyes open. They are able to climb onto their mother's abdomen with a strong grip with little or no assistance. They depend on their mother's milk until they are gradually weaned at 2 and a half months. Young achieve independence as early as 5 months.

Habitat:C. didactylus are typically found in very wet tropical areas, where the annual
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Mother and Baby Sloth by the Bridge at La Selva Biological Station
rainfall exceeds 2,000mm and the dry season is short. They prefer warm humid conditions with moderate to dense tree growth. They utilize vines and interconnecting tree crowns to move from tree to tree, so they prefer areas where these are abundant. They can usually be found in the upper forest canopy at heights 24-30 meters above the ground.




Ecology:
The two-toed sloth is a slow-moving nocturnal mammal that has acquired several energy-conserving adaptations to adjust to their low-calorie diet that consists mostly of leaves. The sloths best defense against predation is their ability to camoflage with their surroundings. Moving through the canopy ever so slowly allows them to go undetected by potential predators.
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Sloths act as a vehicle for a lot of arthropods including mosquitos, sand-flies, triatomine bugs, lice, ticks and mites. There are 2 species of ticks from the genus Amblylomma that are specialized for living on sloths and they are rarely found on other animals.






Behavior:
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Baby Two-Toed Sloth Clinging to its Mother

The two-toed sloths are usually
found in solitude or females
carrying an offspring. They only
join their partner during the
mating season. There is a strong
connection between mother and
offspring in the early months of
the young's life (Felton-Church). We saw just this pattern on our trip to Costa Rica. We saw a mother and baby two-toed sloth, as pictured. But when the sloths weren't in this mother-offspring pair they were seen alone sleeping upside down from a branch during the day. They were usually pretty high up in the trees too, which is common for this species.


Diet:
What?
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Eating His Greens
Cecropia leaves are the most common plant that the two-toed sloth munches on. The diet of wild C. didactylus is mostly composed of young shoots, leaves and fruits, though they will occasionally eat insects, eggs, nestlings, carrion or small vertebrates. C. didactylus in captivity are know to eat a wide variety of foods such as salad, grains, leaves, cooked rice, carrots, kale, sweet potatoes, apples, bananas, green beans and peas.

When?
Two-toed sloths are nocturnal so they consume their meals at night.
Where?
The two-toed sloths move about the trees in search of food, eating the leaves, fruit and seeds as they find it. At rescue centers, such as the Sloth Sanctuary in Costa Rica, the
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Snacking on Flowers
sloths are fed a combination of different foods that have been proven to promote their health and well-being while being in captivity. When we visited the sanctuary we got to see snack time. It turns out that sloth babies enjoy snacking just like humans.





Other Species Interactions:
Bradypus tridactylus (the three-toed sloth) and C. didactylus diverged from a common ancestor about 40 million years ago, however they are often found in sympatry. Their ability to partition resources allows them to avoid interspecific competition and thus flourish while sharing a habitat.

C. didactylus also share their tree habitat with several different species of monkeys, but due to their capacity for below-branch feeding they can avoid too much competition with them. Also the sloths have a low metabolic demand and a specialized gut compared to the monkeys, so C. didactylus may not have a large impact on the monkeys.


Sloth Sanctuary in Costa Rica:

This is the sloth sanctuary that we traveled to in Costa Rica. They are making a tremendous effort to rehabilitate injured sloths and return them to the wild. When the sloths are incapable of returning to the wild safely, the sanctuary provides them with food, shelter and a habitat as close to nature as possible. It is a great project, check it out!



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Citations:
Adam P.J. 1999. Choloepus didactylus. Mammalian Species No. 621. American Society of Mammologists 1-8.

Felton-Church, A. 2000. "Choloepus didactylus" (On-line). Animal Diversity Web. Accessed April 18, 2010 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Choloepus_didactylus.html.