Jellyfish Facts for Kids - What is a Jellyfish?

Have you ever seen a jellyfish?

It looks like an umbrella with projections, called tentacles, hanging down from the edges.
The body of a jellyfish is like a hollow bag with thick sides. These sides have an "outer skin" and an "inner skin."
Between these two "skins" is a jelly-like substance. This substance gives the jellyfish its shape.
Jellyfish live in the sea, but they are not fish. 
Fish have backbones and move forward by swimming. Jellyfish do not have backbones, and they move up and down in a unique way.
They expand like an opening umbrella, then pull together again rapidly. This squeezes water out from beneath, and the jellyfish moves upward.
Jellyfish eat small sea animals after stinging them with their tentacles. 
The tentacles are covered with thorny threads. When another animal bumps into the jellyfish, these threads lash out like tiny, poisonous whips.
The threads paralyze the victim, and the jellyfish then uses its tentacles to pull the trapped animal into its mouth.

The tentacles of a jellyfish are covered with tiny capsules.
Inside each capsule is a thorny stinging thread.
The jellyfish whips out these threads to paralyze small animals.

DANGER!

If you see a jellyfish, even one that has been washed up on the beach, don't touch it.
The poison from some jellyfish stings can be deadly to human beings. 

Anyone stung by a sea wasp, a kind of Australian jellyfish, will almost certainly die within a few minutes.

But common jellyfish sting do not kill.

Jellyfish and corals belong to a group of invertebrates called coelenterates.
The term coelenterate means "hollowbody."
Some species of jellyfish produce their young from eggs.
The eggs grow into hollow cylinders, called polyps, which attach themselves to the seabed.
New jellyfish start to grow on these polyps.
Each bud of a mature polyp looks like a tiny saucer.
When a bud is big enough, the polyp releases it into the sea and it grows into an adult jellyfish.