Jellyfish Facts

Jellyfish have been on the earth for millions of years, far longer than even the dinosaurs.

There are many different types of jellyfish in all of the oceans; some are harmless and some are very dangerous.

Jellyfish Facts for Kids

  • Jellyfish is a name given to the sea creatures that seem to be made up of a kind of gelatinous substance. They are actually made up of protein and water.
  • Some jellyfish can grow as large as a human being, while others are as tiny as the head of a pin.
  • People in some countries consider jellyfish a type of food.
  • Jellyfish do not have any brains, but some types do have eyes.
  • Jellyfish that sting is called ‘medusae’.
  • Jellyfish that group together are referred to as a ‘smack’
  • Jellyfish cannot swim but must drift along with the tides of the oceans. When a large number of jellyfish end up in the same area due to the tides it is called a ‘bloom’.
  • Each of the jellyfish species has a different lifecycle. Some can live for just a couple of days, while others can live as long as a year.
  • Jellyfish reproduce with both male and female and create the tiny ‘planulae’ that falls to the ocean bottom. Each of the ‘planulae’ will form polyps and those create small buds that end up being the baby jellyfish, called ‘ephyrae’.
  • Jellyfish that sting actually has long tentacles with stinging cells at the ends. They are designed for capturing their food and injecting toxins to allow them to eat.

Jellyfish do eat a variety of food types: phytoplankton, which is a small plant, as well as fish eggs, larvae, planktonic eggs, copepods, and all types of small marine animals.

Some types of jellyfish will actually eat other kinds of jellyfish.

The danger of too many jellyfish is that they eat many of the kinds of foods that fish eat. When the food is gone, the fish don’t have anything left to eat.

Various parts of China and Japan have been experiencing a huge population growth of jellyfish.

The numbers are so great that they are eating all of the food, getting caught in fishnets, and even washing up onshore.

Some people have taken action by trying to dredge jellyfish up to remove them, but they end up with tons of jellyfish on the ships and the problems keep continuing.