How, evolutionarily speaking, did sloths come to be the slow-moving creatures they are today? I’m not saying I can’t imagine how hardly moving might come in handy in some situations. But how exactly did and does their mating select for that? Do adult male sloths hold races in which the females choose the loser? Do the females stare at a group of eligible males and wait until all but one have moved?
It probably had to do with energy usage. As far as I know they are herbivores. Its takes a lot of eating to get energy out of leaves and only so much eating can be done in a day. They probably move slowly because it is more efficient than moving quickly, there by leaving more energy for getting it on. Their speed was probably determine not by how slow they could go, but by how slow they could get away with going. They live in the trees and I don’t think that they have any real predators up there that they have to run away from, so why not just be efficient with their energy usage. Interestingly, I’ve seen video of them swimming (exposed to predators) very quickly between trees during the flooding season.
Sloths, unlike most mammalian herbivores, feed on mature leaves, which contain little protein and other nutrients and are difficult to digest. (Most other mammals that eat leaves tend to eat mostly young leaves, which have a higher nutritional content and which are easier to digest.) This is a low-energy ecological strategy. Although they yield little energy, mature leaves don’t require a lot of energy to find or eat. Much of the energy involved in using them is in the digestive process itself, which the sloth can carry out even while it sleeps.
Sloths have predators in the trees, especially Harpy Eagles, but they avoid predation because they are very hard to see when they are not moving, which is most of the time. They look like a big clump of moss.
Sloths have not been selected to move slowly. Rather, there is little selection on them to move fast, so they don’t.
Or maybe female sloths find rampant moss infections hot…
They want a man with a slow hand.