Sep 07, · Adult Jellyfish are either male or female. Both of them possess organs used for sexual reproduction called gonads. When an Adult Jellyfish reaches its maturity and is ready to mate, the male Jellyfish releases sperms through the only opening in their body, the mouth. The mouth is located on the bottom of the bell. In jellyfish the transparent mesoglea layer is quite thick. The life cycle of free-swimming scyphozoan jellyfish typically consists of three stages. A sessile polyp (scyphistoma) stage asexually buds off young medusae from its upper end, with each such ephyra growing into an adult. The adults are either male or female, but in some species they change their sex as they age.
The body of an adult jellyfish is composed of a bell-shaped, jellylike substance enclosing its internal structure, from which the creatures tentacles suspend. Jellyfish come in all different shapes and colours and range in size from 3 millimetres to 3 metres in diameter.