Despite their name, jellyfish, in fact, are not fish at all. They are free-swimming invertebrates - no backbones - with a saucer-shaped body that is typically transparent and has stinging tentacles around the edge. Jellyfish have tiny stinging cells in their tentacles to paralyze their prey before they eat them. While some stingers are deadly, others will only hurt to be stung. Jellyfish live in multiple oceans and there are many different species. Jellyfish are interesting creatures.