You're a Jellyfish!

You're a Jellyfish!

Floating at Sea Imagine that your body is shaped like a bell, and you have long tentacles streaming down under you. You are mostly made of water and cannot survive away from it. You live in the ocean and travel by floating gracefully on currents. You're a jellyfish, or jelly, and not a fish at all. You're a kind of invertebrate--an animal that has no backbone.

You and your jellyfish cousins live in every ocean in the world. Some also live in lakes and ponds. Some live in warm water, and others prefer cold water. Some of your cousins are survivors--they've been around for 650 million years, since long before the time of dinosaurs.

Jelly Bodies Like all jellyfish, you have no brain, heart, blood, or bones. Your body is made of water, muscles, and nerves. You use your eyespots and nerve network to sense up and down, light and dark, and the world around you. The main part of your body is your bell. Tentacles hang from around your edges like fringe. A mouth and digestive sac hang in the center. Some of your cousins have frilly oral arms, or mouth arms, around this sac.

You and your cousins come in many shapes, sizes, and colors. Jellyfish that live near the ocean's surface are often clear, or see-through. Jellies that live deep in the ocean may be red or purple. Some jellies are white with splashes of color. Some deep-sea jellyfish even glow in the dark!

Getting Around As a jellyfish, you spend most of your time drifting on ocean currents. But you can also move when you want to. First you let your bell fill with water. Then you squeeze the muscles in your bell the way a person blows a bubble with bubble gum. As you force water out of your bell, you shoot forward.