Mr. Catron,
Here is the answer to the question. The polysaccharide found in the skeletons of insects, crustaceans, and arachnids is chitin, which is a polysaccharide, the monomer unit being glucosamine. It is used industrially in purifying wastewater, thickening and stabilizing food and pharmaceuticals and much more.
Luke McFadden, Billings West High School