Tuesday, December 6, 2011
ABC Wednesday: U is for Unau
A Unau is a two-toed sloth (Choleopus didactylus). The Choleopus family has two species, the other one is Hoffmann's two-toed sloth), and both species have two toes on their forefeet, but three on their hind feet. You can see this very nicely here
Three toed sloths have three toes and three fingers. There used to be other sloth families, but they all died out (like the ground sloths). All sloths are native to the rainforests of Central and South America.
Unaus eat mainly leaves and that's the reason why they lead such a relaxed, slow life. Leaves are not very nutritious and so the sloth doesn't do much to conserve the little energy it gets from its food. Their stomach has multiple compartments and their gut flora contains a host of bacteria that help with digesting the leaves.
They are more active than the three toed sloths, though, and can be quite aggressive when threatened. Those claws are not only good for hanging from branches all day long. But usually they are not even spotted by predators, a sloth is very well camouflaged. Their fur often contains cyanobacteria and turns green, making the sloth even more invisible. Some sloths even are host to moths, who probably feed on the bacteria.
Sloths are very good swimmers, but they can only crawl along when they come down to the ground. They do that once a week or so to visit a midden where they bury their faeces. It's possible that they do that to avoid making any noise that would attract predators - during the rainy season they don't bother climbing down to defecate and the rain would definitely cover any noise that makes.
Sloths give birth to one baby and the mother carries it around with her for almost a year, although the baby will be weaned after only a month, feeding on leaves the mother already chewed at first and then finding leaves on its own. Mature at three years, Unaus can reach an age of 30 years. They are not considered threatened, since they are widely distributed - but considering the rapid destruction of the rainforest, I'd say it's only a question of time.
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The sloth photos were taken at Wilhelma, Stuttgart.
Sources and further reading:
Chou Ai, Sloth Health Centre