This is a cross section of northern pike intestine in which a Proteocephalus pinguis can be seen attaching by pinching up small pieces of the intestinal mucosa into its suckers. This section is stained with a special dye that stains connective tissue red. The dark red band at the bottom of the photo and the fine matrix of connective tissue above it are normal. Note that there is no sign of unusual connective tissue deposition at the site of parasite attachment. This parasite does not cause any damage to the host's intestine, which is fortunate because hundreds or even a few thousand of these tapeworms may be present in a single fish.