Moth-to-Sloth Food Web


Besides the risks three-toed sloths incur on their tri-weekly potty trips, the trips are costly in terms of energy demands. Why, scientists wondered, do sloths expend so much energy just to poop? (National Geographic News Watch)

Use our resources to better appreciate sloths and the people who love them.

David Attenborough is one of those sloth-loving people.

Discussion Ideas

  • What is the relationship between the three-toed sloth, pyralid moths, and algae? Read our introductory page on food webs to get an idea.
    • The sloth’s body is a micro-habitat with its own food web. Follow the sloth-to-moth web below.
      • Three-toed sloths eat leaves—they’re one of the largest tree-based herbivores in the world. (Here’s another example on the other side of the ocean.) Leaves are very low in protein and nutrients, so three-toed sloths supplement their diet with algae. They don’t have to look very far or work very hard to find it.
      • Algae, a nutrient-rich producer, grows in sloth’s fur. Biologists aren’t quite sure how the algae gets there, but it has something to do with the algae’s sloth-fur neighbors, pyralid moths.
      • Pyralid moth larvae incubate in sloth poop and, after they’ve hatched, the moths live in sloth fur. “Insect droppings could be seeding sloth fur with extra nitrogen, or the moths could be transporting the sloth’s own dung back to the animal,” according to the Nat Geo News Watch post.
  • Three-toed sloths are notoriously difficult to maintain in zoos or other captive-breeding facilities. Few have survived more than a month. How might the new discovery of the moth-to-sloth food web help explain this?
    • Pure speculation and hypothesis: Zoos and zoo animals are usually kept very clean. This “highly sanitized environment” might not support the dynamics of the moth-to-sloth food web. For instance, zoos might not be allowing sloth poop to slowly decompose and incubate pyralid moth larvae. Fewer moths could then colonize “cleaner” sloth fur, reducing the amount of algae available to supplement a sloth’s diet.

One thought on “Moth-to-Sloth Food Web

Leave a Reply