US Person has been uncharitably compared to a sloth presumably because he is not currently a member of the workforce. But dear reader, consider the sloth: the three-toed variety to be exact
(Bradypus variegatus). It is a marvel of energy conservation and benevolent mutalism. The sloth is a complete ecosystem in itself and a rather engaging animal with its permanently displayed smile and almost mesmerizing slowness, resembling a dullard TV presenter on opiates. The three-toed (actually fingers) is not closely related to the comparatively frenetic two-toed sloth which is classified in a different family. Sloth spends its apparently
lazy days in a favorite tree and only comes down to defecate on a midden pile once a week. This behavior is an adaptation to its low energy diet of leaves and the presence of numerous predators on the ground. Most sloths meet their demise on the ground. Once it was thought that the sloth was risking predation and using 8% of its daily caloric intake to fertilize the home tree with its excrement since two-toeds excrete freely from the trees. But
a recent study has exposed the amazingly active inner life of the sloth which on the outside seems solitarily serene.
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| Farmer sloth |
The pyramid moth lays its eggs in sloth dung; it develops to have an even more intimate relationship with sloth. After hatching from the dung cradle, young months fly up into the tree. Some land on the slow moving mammal, loose their wings, and take up housekeeping in the sloth's shaggy coat. Comb a sloth's fur and dozens of moths will fly out. The moths get a warm, safe place to live and reproduce that does not move too fast for their comfort. Even when sloth scratches, it does so in slow motion which the moths easily avoid. Perhaps the moths earn their room and board by consuming other unbeneficial insects inhabiting the microcosm. They do increase the amount of nitrogen in the sloth's coat; when they die, their remains are consumed by bacteria and fungi also living in the furry forest.
The major survival challenge facing the sluggish animal is obtaining enough energy from its leafy diet. Arboreal sloths have the slowest digestion of any mammal. Slow-motion is an evolutionary adaptation to cope with its diet constraint. Koalas are another foliar mammal that has adopted slow living. The sloth has also accomplished a unique, self-contained solution to this energy budget problem. Moss may not grow on slow sloth, but algae does. Why does algae grow in hollow hair fibers on sloth? Because algae uses the nitrogen, water and sunlight in sloth's fur. Following their hypothesis, researchers found algae in the digestive system which is evidence sloth supplements its low-nuitrition diet with a high-nutrient food source growing in its fur. So although the sloth lives in the slow lane, it is actually a self-contained and complex ecosystem--a mobile algae farm--that converts energy into food for its host without any technology at all. Clever sloth!