Moon Jellyfish

Like other species in the genus, the jellyfish is almost entirely translucent, usually about 25–40 cm (10–16 in) in diameter, and can be recognized by its four horseshoe-shaped gonads, easily seen through the top of the bell.

It feeds by collecting medusae, plankton, copepods, mollusks, and fish eggs with its short, fine tentacles, and bringing them into its body for digestion. The sting has a mild effect on humans, with most having little or no reaction. It is capable of only limited motion, and drifts with the current, even when swimming.

A. aurita is endemic to the northeastern Atlantic Ocean, including the Baltic Sea where the 1758 type specimen was collected. Established populations are also found in the Northeastern United States and Argentina, where they were introduced (although natural dispersion to the United States can't be ruled out). A single specimen has also been found in the Pacific Northwest.

The life cycle of Aurelia aurita is similar to other species in the genus, consisting of two main stages: the free-swimming medusa and the benthic polyp, also known as a scyphistoma. During the medusa stage, A. aurita reproduces sexually, as opposed to the asexually reproducing polyp stage. The scyphistoma stage can survive for months without feeding, and have been shown to have relatively low feeding selectivity. In this stage, A. aurita can adapt to several different environmental conditions. They can be found in estuaries, bays, fjords, and polluted waters, among other habitats.