Sloth guts are designed for hanging upside down

Three-toed sloths have a unique abdominal design -- their innards fixedto their lower ribs to avoid squashing the lungs while hanging upside down, a studysaid Wednesday.The South and Central American forest dweller, also known as the brown-throatedsloth, spends a large part of its life hanging from its hind legs to reach young,tender leaves growing on the tips of branches, as well as to groom.With its slow metabolism, it may take the sloth a month to digest a single leaf, andit can store a third of its bodyweight in urine and faeces -- which it deposits aboutonce a week."This means that the stomach and bowel contents make up a considerableproportion of their body mass," said Rebecca Cliffe of the Swansea Laboratory forAnimal Movement in Wales, who co-authored the study in the Royal Society journalBiology Letters."With their limited energy supply, it would be energetically very expensive, if notimpossible, for a sloth to breathe whilst hanging upside down," she told AFP.Cliffe and a research team say they believe they solved the riddle: numerous uniqueadhesions in the abdomen anchor organs such as the liver, stomach and kidneys,thus preventing them from pressing on the diaphragm when the sloth is inverted. "These seemingly innocuous adhesions are likely to be important in the animal’senergy budget and survival," said the study.They could reduce a sloth's energy expenditure by 13 percent, added Cliffe.