Sloth slings

British zoologist Becky Cliff of Swansea University has discovered something new about one of my favorite animals: sloths! While these tree-dwelling creatures are often photographed hanging from branches by all fours, she has observed that they spent a lot of time dangling by their legs upside-down so that they can reach the most tender leaves. This would be a big problem, since the weight of all their organs – and not to mention the waste products in their system, since they only urinate and defecate once a week – would press down on their lungs and diaphragms and make it very difficult to breathe in that position. But when Cliff autopsied sloths that had died natural deaths, she found fibrous membranes attaching the organs to the animals' ribs and hips. As she says, "It would be energetically very expensive, if not completely impossible, for a sloth to lift this extra weight with each breath were it not for the adhesions."

 

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