ocean

jellyfish, also called aguamalas, malaguas, aguavivas, aguacuajada or tears of the sea, are marine animals belonging to the Cnidaria phylum (previously known as coelentéreos); they are pelagic, with a gelatinous body, with the shape of a bell from which hangs a tubular handle, with the mouth and at the lower end, sometimes prolonged by long tentacles loaded with urticating cells called cnidocytes. They appeared about 500 million years ago in the Cambrian.1

To move through the water is driven by rhythmic contractions of your entire body; takes water, which is introduced into its gastrovascular cavity and ejects it, using it as "propellant".

The concept of jellyfish is not taxonomically but morphological. Many cnidarians have an alternation of generations, with sessile polyps that reproduce asexually and pelagic jellyfish that carry out sexual reproduction. Only anthozoans lack a jellyfish form; the other three classes of cnidarians (hydrozoans, scyphozoa and cubozoans) have polyp form and jellyfish form; said jellyfish have distinctive characteristics in the three classes, so that we can speak of hydromedusae, squamomed jellyfish and cubomedusa respectively.