While it's widely known that the species which spends the greatest percentage of its time in sleep (100%) is the Norwegian Blue, it should be noted that the Norwegian Green Sloth (its colour derived from the presence of symbiotic cyanobacteria), which, like its South American cousins, swims well, has been observed fording for the pines.
As noted by Wikipedia, "Females normally bear one baby every year, but sometimes sloths' low level of movement actually keeps females from finding males for longer than one year." Which could explain difficulties in getting sloths to breed in captivity: the lack of excitement in the chase. Some breeders have reported success after playing the following at 33 1/3 rpm:
While "sloth" is a human trait, I find sloths themselves, reflexively speaking, given that I myself am slothful, to be alien, and wonder why their coats, like those which hang in a closet too long, aren't ravaged by moths.
Ode To An Omen Of Acherontia Atropos
Or: Bend & Break Sinister
Come winged dryad of the breeze,
Come friendly boughs and fall on sloth,
And crush the cradle of the trees,
Good night for death, good night for moth.
(Apologies to Nabokov, Keats & Betjeman)
*Hat tip to Un Chien Andalou