Aurelia aurita

We are facing what is possibly one of the most common and cosmopolitan jellyfish among them. Aurelia aurita is a cnidarian belonging to the order Scyphozoa and the family Ulmaridae, which together with 25 other species make up the genus Aurelia. We can find specimens of this species throughout the planet, except for the very cold waters of the poles. They alternate during their life cycle, stages with benthic polyp phase, and free-living jellyfish phase in surface waters where they are dragged by the prevailing currents. They inhabit both the waters closer to the coasts as well as the high seas.

The body of Aurelia aurita is circular, bell-shaped and with a maximum diameter of 25 to 40 cm. The body of the bell consists of a translucent surface with slightly bluish or pinkish tones, and a transparent whitish interior. Bordering the bell, technically called umbrella, we find hundreds of long and thin filamentous tentacles loaded with stinging cells, with which it captures its prey, mainly placton, although occasionally it can capture small invertebrates such as polychaetes, protozoa, diatoms or ctenophores. In the center of the body, given its very high transparency, we can clearly observe 4 horseshoe-shaped gonads, arranged symmetrically. In male specimens, these gonads have whitish or yellowish colors, while in females they are pink or purple.

The jellyfish Aurelia aurita swims by performing a contraction movement of the bell through periodic undulations, which give it a certain degree of control of the movement, although they are usually dragged by the currents.

The jellyfish phase of Aurelia aurita reproduces sexually, a process by which gametes from both sexes fuse to form an egg that develops inside the gonad of the female specimens. After an incubation period, a free-living larva hatches and becomes part of the plankton until it settles on the rocky bottom to form the polyp stage. The polyp phase usually lasts approximately 3 months, and at its end the specimens reproduce asexually forming small free-living jellyfish.