Class Scyphozoa 

Scyphozoans, commonly known as true jellyfish, are exclusively marine cnidarians that have a dominant medusa stage and a short-lived polyp stage. Their medusa is typically large and umbrella-shaped, covered in a thick layer of mesoglea, giving the body a gelatinous consistency. They have radial symmetry, typically in multiples of four, along with tentacles that are equipped with cnidocytes that contain nematocysts that they use for capturing prey and defense. They have a gastrovascular cavity, divided into four gastric pouches with radial canals that distribute nutrients throughout the body. The mouth is located on the underside of the bell, and they typically have oral arms that help bring food inward. They also have rhopalia, sensory structures that contain statocysts for balance and ocelli for light detection, allowing them to have more coordinated movements. Locomotion is through rhythmic contractions of the bell, but many species drift with the current.