Jelly fish are increasingly present in the ocean because they can survive in a less clean environment. They are made mainly by water. Is a known fact that turtles eat them. Now biologists found that penguins eat them even though they are very low in calories.
Japanese dry them and sell them under the name of kurage. The yellow crunchy strands in sea weed salad is kurage.
Italian Chefs are trying to use them in tasty recipes.
Note: when dry they do not sting.