Diphyllobothrium:
Metazoa Platyhelminthes Cestoidea Pseudophyllidea Diphyllobothriidae Diphyllobothrium

This parasitic tapeworm infects humans who have eaten uncooked or undercooked contaminated fish. An adult can grow to be anywhere from 3 to 10 meters long and is capable of producing one million eggs per day. Symptoms of infection may sometimes be absent; however, most people experience digestive discomfort, abdominal pains, nervous disorders, or anemia. In addition, you may experience vitamin B12 deficiency if the worm lodges near your small intestine.