A+E Networks. In Tokyo, Commodore Matthew Calbraith Perry, representing the U.S. government, signs the Treaty of Kanagawa with the Japanese government, opening the ports of Shimoda and Hakodate to American trade and permitting the establishment of a U.S. consulate in Japan.
Platyhelminthes are mostly worm like creatures that are dorsoventrally flattened, meaning they look like a ribbon, this is why they are called names such as Tapeworm, Flatworm, Fluke and Planarian. The Platyhelminthes are a successful phylum with around 25,000 known species divided into four classes. Most Platyhelminthes are parasites on other animals, only the Turbellarians are mostly non-parasitic. A few species are commensalists living in harmony, or mutual benefit with another, normally larger organism. Most species feed on animal material either as parasites or as scavengers, a very few species feed on algae.
Phylum Platyhelminthes (the flatworms) ~1300 species ie: Planarians, Tapeworms, Flukes Some are free living and some are parasitic. Soft, flattened worms with tissues and internal organ systems. The simplest animals to have 3 germ layers, bilateral symmetry, and cephalization.