In fact, some species are some of the largest types of plankton on earth. Scientists classify plankton as a plant or animal at the mercy of the currents something that can t swim against the currents under its own power. This makes a jelly a kind of zooplankton. But jellies are so much more. Jellies belong to the phylum Cnidaria.
All cnidarians share similar characteristics.
Scientists call their body shape a medusa. It resembles the Medusa of Greek mythology. In the legend, Medusa s face was surrounded by a ring of snakes, similar to the tentacles of a jelly. Instead of biting snakes, however, each tentacle of a jelly is filled with stinging cells called cnidocytes. These specialized cells are used for defense and feeding and contain small stinging structures full of toxins called nematocysts.