Sloths have a short end in many ways. Who wants to be named after a deadly crime? Nor is it merely an English quirk to call them “sloths”; Other languages have names around terms like “lazy”, “slow” and “sleep”. The three-toed sloth’s scientific name, Bradypus, means “slow feet” in Greek. Only their cute, slightly confused looks worthy of an Internet meme can save them from being written off as completely useless.
But sloths are much more than just small bags of laziness. Here’s a fact about sloths to change their bizarre lethargy in the animal kingdom.
A fun little fact is that almost all mammals have the same number of vertebrae in their necks. From short-necked gibbons to stretched-out giraffes, mammals all seem to manage with seven cervical vertebrae. Sloths don’t play by these rules, however, and confusingly may have more or fewer vertebrate. Two-toed sloths may have anywhere from five to seven, and three-toed sloths have eight or nine, depending on the species.
Normally, any alteration in the genes that deal with vertebrae would be debilitating for any animal. It seems, however, that the slow pace of sloth lifestyle has given them flexibility when it comes to changing their spines. Having a nutrient-poor diet means having a large digestive tract, comprising up to half a sloth’s weight. It could be that moving the ribs forward or backward with relation to the neck helps them to fit more gut in. But this is pure conjecture, and the mystery of sloth necks remains to be solved.