Jellyfish are the most fragile kinds of fish in the ocean and all jellyfish have a very good ability to sting. Jellyfish can sting people but they are not really harmful to people. Jellyfish tentacles can be as long as 50 to 500 inches long. Jellyfish are made out of more than 95% water and have no heart, bone, brains, gills, blood or eyes. The jellyfish's mouth is in the middle of its tentacles. There is one central nerve in the jellyfish that makes up its internal structure. If the jellyfish didn't have that nerve, it would not be able to move around. There are over 200 different kinds of species of jellyfish in the ocean. Jellyfish can be spotted in 35 states out of the 50 states.

All jellyfish go through 4 different stages. In the first stage, the planula larva is like the egg when it is first hatched by exiting from the mouth or brood pouches of a jellyfish. In the second stage, the planula larva then looks for a shaded area and attaches themselves to the bottom forming polyps. In the third stage, these polyps divide and bud into young jellyfish called ephyra. In the last stage, these ephyra will grow into adult medusa in a few weeks. The medusa can grow to the size of a quarter. If a jellyfish is located in a Rhode Island lake, it can be the size of a dime. Jellyfish live for about 3 to 6 months.