How many species of jellyfish are there? Jellyfish are sometimes called sea jellies. They belong to a group called Medusozoa which is divided into four classes: Hydrozoa, Scyphozoa, Cubozoa and ...
They're not jellyfish." Brulot posted photos of the ... a marine organism that falls under the class of hydrozoa. It can grow to a length exceeding the blue whale and is rarely seen so close ...