I have just experienced one of those biological “well I never” moments that makes biology such a fascinating pursuit. This I have to share with you.
In a book I am reading (details at the end) I found the following. Quote:
“Another example … is the unusual bathroom behaviour of sloths. Three-toed sloths spend nearly their entire lives in the forest canopy. The ground is the most dangerous place for sloths because there are hungry, toothy predators down there like jaguars and feral dogs. Once a week, however, sloths break their arboreal habits and head to the ground to take care of some personal business. They slowly climb down to the forest floor to defecate.
On the surface, this behaviour is baffling. Why risk the chance of encountering a predator? Why not just let it fly from the branches?… Are sloths fertilizing their trees in a targeted manner? Is it some way of marking their territory? Is it an atypical type of mate attraction?
Acutely observant scientists solved the mystery only recently with a great deal of patience. They first observed that sloths have algae growing in their fur, which gives the sloths a green tint. The algae help the sloths blend in with the forest canopy, but the story goes beyond organic camouflage. The sloth scientists noted sloths feeding on their homegrown algae and in doing so, supplementing their otherwise nutrient-poor diet. Eating their own fur algae is admittedly weird, but it gets even stranger than that. A population of moths lives in the fur of each three-toed sloth. The moth population increases the nitrogen content of the fur and thus promotes the growth of the algae the sloths snack on. When the sloths make their weekly treks to the bottoms of trees, the female moths lay their eggs in the fresh sloth dung. The tidy sloths cover up their mess with some leaf litter, and after the eggs hatch, the moth caterpillars dine on the sloth poop, grow up, become adults, and fly to the canopy layer to colonize sloths just as their parents did.”
Like I said, if don’t study biology you risk missing out on knowing things like this … and I’m not being flippant in saying that. It’s rather wonderful that evolution has put together all the parts that make this behaviour a reality. So many needs for a mammal, some algae and a moth neatly packaged and solved.
(from “Evolution Gone Wrong: The Curious Reasons Why Our Bodies Work (Or Don’t)” by Alex Bezzerides)
Seems a remarkably contrived piece of evolution. Methinks there is another link in the chain that we are missing.