These tapeworms of dogs have taken sexual reproduction to the extreme. Not only do they have multiple proglottids, but there are two complete sets of reproductive structures in each proglottid! They also have an unusual life cycle modification in which the egg is eaten by a larval flea, and the parasite survives metamorphosis of the flea so that when the flea finds a new dog to infect, the dog can acquire an infection by swallowing the flea during grooming.