Elder offspring (age 6.5): I can’t wait for Friday! We get to do science in school!
Younger offspring (age 4.5): We do nature study every day.
Dr. Free-Ride: That’s because you don’t have standardized tests yet, or the science would get crowded out by all the other stuff on the test.
Elder offspring: We’re learning about the life-cycles of different animals. And, we have two bearded dragons in our science classroom.
Younger offspring: We’re learning about marine mammals, but Aidan C. and I call them “gaREEN mammals”.
Dr. Free-Ride: Green mammals? You two are silly, aren’t you. Hmm … are there any green mammals?
Dr. Free-Ride’s better half: Sloths.
Dr. Free-Ride: Sloths?
Dr. Free-Ride’s better half: Sloths. An algae grows on them* and helps them blend in with leaves.
Dr. Free-Ride: Cool! Like what happened to the polar bears at the zoo when there was algae growing in their hair shafts.
Younger offspring: What other color mammals are there?
Dr. Free-Ride: When you guys were babies I fed you lots of carrots to see if I could make you orange mammals.
Elder offspring: Did it work?
Dr. Free-Ride: It did not. Is there no mammal that I can turn orange by feeding it lots of carrots?
Younger offspring: Not one that you can turn orange.
* More on green sloths:
The Value of a Green Back
What I find most interesting about the three-toed sloth is the symbiotic relationship it has with other organisms. One effect of the sloth’s languid pace of life is that it can’t be bothered to groom itself. This turns out to be beneficial to several varieties of algae and mold that grow inside the sloth’s hollow hairs. The algae effectively turn the sloth green, giving it excellent camouflage among the leaves. The camouflage is crucial to the sloth’s survival, because its inability to move quickly makes it an easy target for the harpy eagle.
But the symbiosis doesn’t end there. The algae in the sloth’s fur provides food for a great many insects. (I should point out, incidentally, that sloths have extremely long fur, making them appear much larger than they really are.) Beetles have been found by the hundreds living on a single sloth. Another insect that calls the sloth home is a type of moth — Bradipodicola hahneli (or “sloth moth” to most people). The sloth’s fur provides both food and protection for the moth. Not only does it feed on the algae, but it also deposits its eggs in the sloth’s droppings, where they pupate and hatch, and then fly off to look for another sloth to live on.