A jellyfish is not a fish. It's an invertebrate, an animal with no bones. It also has no brain, no heart, no arms and no eyes. There are many different kinds and sizes of jellyfish. Some jellyfish are smaller than an inch and others are larger than 7 feet, with tentacles that extend over 100 feet.
A jellyfish's body is shaped like an upside-down bowl. Its mouth is inside the bowl at the center. Jellyfish or "jellies" have soft bodies called bells. The bell moves in and out like an umbrella opening and closing. Its mouth is on the bottom of its body.
Have you ever been stung by a jellyfish? We get stung when we walk or swim in their path. Most stings from a jellyfish hurt a little, but some jellyfish stings can cause heart problems or even kill people. Box jellyfish, also called the "sea wasp", are one of the deadliest animals on Earth. They live in the ocean waters north of Australia.
Jellyfish sting to catch food and protect themselves. Jellyfish use their long poisonous tentacles like fishing line to catch and sting their prey. The tentacles have hundreds of special stinging cells that are full of venom.
Jellyfish live in oceans around the world. Due to climate change, there are more jellyfish because the oceans are getting warmer.