How long does a jellyfish live for?

Jellyfish live an average of about a year, although they can live much longer in captivity. Their lifecycle takes one year to complete. Juveniles are produced frompolyps in the spring and adults grow throughout the summer. Towards the end of the summer males and females mate and produce polyps, which grow and divide throughout the winter. In the spring the polyps start producing juveniles and the cycle repeats. This means that the swimming medusa life stage of jellyfish is only around for a few months during the summer. Jellyfish have delicate tissue, so they are usually damaged by the end of summer and most of them die. However, in captivity jellyfish can live much longer. It is not unusual for people to keep their pet jellyfish alive and healthy for 10 years or more if they feed them consistently.