What is a "jellyfish"?

A jellyfish is a gelatinous marine animal that belongs to the phylum Cnidaria. They are characterized by their umbrella-shaped body and long tentacles that contain specialized cells called cnidocytes, which can inject venom into their prey or predators. Jellyfish come in a wide variety of sizes, shapes, and colors, and they can be found in oceans worldwide. They move by contracting and relaxing their bodies, allowing them to drift and swim through the water. While some jellyfish species are harmless to humans, others can deliver painful stings. Despite their simple body structure, jellyfish play important ecological roles and are fascinating creatures of the sea.