Diphyllobothrium latum
An important cestode of humans and fish-eating mammals. They are long tapeworms with an unarmed scolex. D. latum occurs in arctic and near arctic regions. Humans act as final host, but dogs may be infected. Causes anaemia because of its avid uptake of dietary vitamin B12. Eggs release a motile larval form which develops further in aquatic copepods and ascends the food chain, from fish, to humans.