The many-ribbed jellyfish is recognizable by its dark bell which features a network of brown to dark blue channels converging from the edges to the center. Long, slender tentacles extend from the bell. This jellyfish is a hydromedusa with a maximum diameter of up to 10 inches.

The many-ribbed jellyfish is not very stinging unlike its cousin the purple-striped jelly !

The many-ribbed jellyfish mainly inhabits the warm waters of the North East Atlantic Ocean, the Indian Ocean and the Caribbean Sea. It is only rarely found in the Mediterranean Sea where it has started to make occasional repeated appearances.

The many-ribbed jellyfish feeds on small prey that become trapped in its tentacles, which act like fishing nets.

Like all hydrozoan jellyfish, the many-ribbed jellyfish follows a reproductive cycle that alternates between asexual and sexual phases. Initially, polyps attached to the seabed in colonies transform into male and female jellyfish. These jellyfish then release gametes into the water, leading to the fertilization and development of larvae. These larvae settle on the seabed and form new colonies of polyps.

Like other jellyfish species in the Aequoreidae family, the many-ribbed jellyfish also appears to be both luminescent and fluorescent, thanks to two proteins: GFP (Green Fluorescent Protein), which is responsible for fluorescence, and aequorin, which is responsible for luminescence.

The Aequorea jellyfish can be subject to occasional parasitism in the gonads by an amphipod, Hyperia medusarum, particularly during the breeding period

The many-ribbed jellyfish were observed in large numbers floating at the surface along the southern coast of France between St Cyr sur Mer and La Ciotat, and some even washed up on the beaches in April 2021, as well as along the coast of the Pyrénées-Orientales in late May 2023.

When the many-ribbed jellyfish is found stranded on the beach with only its bell remaining, it resembles a bluish pineapple slice.