Researchers discover the cause of whirling disease is a "micro jellyfish"

Photo from: http://science.peru.edu/ 

Researchers from the Univeristy of Kansas have determined that the Myxozoa that causes whirling disease in Salmonidae are included in the jellyfish phylum (Cnidaria).  They are composed of just a few cells and have "one of the smallest animal genomes ever reported: about 20 million base pairs only."

Read more about it here.