Jellyfish release thousands of larvae that settle on the ocean floor and turn into polyps that become baby jellyfish. Male jellyfish release sperm into the water and the sperm either fertilizes eggs that the female releases into the water or enter through the female's mouth and fertilize her eggs.
The fertilized eggs sink to the bottom, often resting on a clam shell or other hard substance. Soon, the eggs will become polyps that have tentacles and the baby jellyfish will begin to feed on plankton. The juvenile will soon turn into a medusa, which is the adult jellyfish with tentacles. Jellyfish only live a few months after maturation.