How does slow movement aid sloths in acquiring food?

One of the reasons that sloths arae slow has to do with their metabolism. They have a very low metabolic rate; this contributes to the speed of their movements. Basically, the higher a creature's metabolic rate, the faster they will move. The slowness of their movements may also aid in how they catch their prey. Other than leaves, they may eat small bugs and lizards, and their slow movements may enable them to go undetected. Hope this helps. 

The slow movement aid sloths in acquiring food is that they are so slow, moving, that algae is able to grow symbiotically in their fur. The Sloth could lick this algae to provide its nourishment. 

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