Arboreal Lifestyle Makes Sloths Slow-Moving Creatures Say Scientists
Posted on July 20, 2016
Sloths are known for being slow-moving creatures. Tree sloths spend much of their time in the canopy munching on leaves. Scientists say this lifestyle is the direct result of the animal's adaption to its arboreal niche. A baby three-toed sloth from Costa Rica is pictured above. A two-toed sloth is pictured below.
Jonathan Pauli, a University of Wisconsin-Madison professor of forest and wildlife ecology, says in a statement, "Among vertebrates, this is the rarest of lifestyles. When you picture animals that live off plant leaves, they are almost all big -- things like moose, elk and deer. What's super interesting about arboreal folivores is that they can't be big."
The researchers found that three-toed sloths possess the lowest field metabolic rate (FMR) of any animals. The increasing specialization has led to lower FMRs. The scientists say the study supports the idea that arboreal folivores are tightly constrained by nutritional energetics. The sloths expend as little as 460 kilojoules of energy a day which is equivalent to burning just 110 calories. This is the lowest measured energetic output for any mammal.
Pauli also says, "The findings reinforce the concept that arboreal folivores are tightly constrained by nutritional energetics. It takes a suite of extraordinary adaptations to survive in forest canopies, and this may help explain the lack of species diversification among arboreal folivores."
Some of the extraordinary adaptations seen in sloths include specialized limbs, low body mass, slow metabolic rate and claws that act like hooks so they can hang in the trees. A research paper on the study was published here in the journal, The American Naturalist.