Up: Photo of Pseudoceros Bifurcus - http://www.inaturalist.org/taxa/135259-Pseudoceros-bifurcus
Pseudoceros Bifurcus, or the Racing-Striped Flatworm is a marine flatworm. It can be found in the Comoros Islands, Madagascar, Heron, and the Central Great Barrier Reef. The immune system of this animal seems to revolve around its mating process. The flatworm is known to have two penises. The two worms stand on their hind legs use their penises to stab the other one, and then injects the loser with semen and the loser will carry the child. This technique is called "penis fencing". The loser, while carrying the child has a hole through them, allowing them to get viral infections that risk their health. The egg begins to produce a chemical called Th2 cytokines which can damage the organs of the mother. To counteract this, the mother produces IL-4 and IL-10 to break down the Th2 cytokines and protect itself from severe inflammatory problems, and the shutdown of the liver. By surrounding the egg, the tissue separates from the Th2 to allow liver to continue to function. The eggs eventually are laid or die off, and it leaves the chemicals still in the body, which could lead to the development of fibrosis.