Just as "pig" is often the go-to insult for someone perceived as messy or greedy, someone prone to lazing around on the couch might be described as a sloth. In fact, the animal gets its English name from the deadly sin of sloth, a profound laziness or "sluggishness of the soul" [source: Suprenant]. But while sloths are by no means fast, with top speeds of just 6 to 8 feet (1.8 to 2.4 meters) per minute, their slow gait conserves energy, and their seemingly inactive bodies are actually working fairly hard [sources: Briggs, Nicholls].
Sloths live in the treetops in tropical climates. Their hairy, slow-moving bodies provide a perfect environment for growing algae and fungus, giving sloths a greenish full-body camouflage. One of the sloth's main predators is the harpy eagle, which has speed and strength and the ability to attack from the air. A sloth has no chance of outrunning an eagle (or a big jungle cat such as a jaguar), so it instead relies on camouflage and complete stillness to make itself nearly invisible.
Contrary to popular belief, sloths sleep only about 9.6 hours each day in the wild [source: Briggs]. As they sit motionless in the trees, their stomachs and intestines slowly and carefully digest the sloth's most recent meal, sometimes taking as long as 50 days to extract every available nutrient from a diet that consists mainly of leaves [sources: Nicholls, World Animal Foundation].