The "fish tapeworm", or Diphyllobothrium latum, is a tapeworm of the Platyhelminthes phylum that is transmitted through fish. This tapeworm is mostly found in the Northern Hemisphere. Tapeworms cannot move on their own so they rely on other organisms to do these actions for them. The fish tapeworm is transmitted from fish to humans through undercooked fish or sushi. The adult worm is composed of three segments: the scolex (head), the neck, and the lower body. The worm starts out in the very beginning stages as eggs in human feces. It is transmitted to a crustacean where it develops into larvae. Over time it makes it's way to a fish, where it grows. It is then transmitted to humans in unprepared fish.