Do the purple jellyfish have a backbone?

No, purple jellyfish do not have a backbone. Jellyfish are invertebrates, meaning they lack a spinal column and are primarily made up of a gelatinous substance. They belong to the phylum Cnidaria, which also includes corals and sea anemones. Their bodies are composed of a soft, umbrella-shaped bell and tentacles, but they do not possess any hard structures like bones.