Moon jellyfish

The moon jellyfish is a common, mostly transparent jellyfish in the genus Aurelia, especially known for its rounded bell and four visible reproductive structures.

The moon jellyfish is a common, mostly transparent jellyfish in the genus Aurelia, especially known for its rounded bell and four visible reproductive structures. It occurs in coastal waters in many parts of the world and is a frequent sight in harbours, estuaries, and aquarium displays. In Canada, moon jellyfish are found in Atlantic and Pacific coastal waters, commonly noted in cooler temperate seas.

Description

Moon jellyfish are saucer-shaped jellyfish with a translucent bell and short tentacles. They typically measure 20 to 40 centimetres across. The four circular markings visible through the bell are the gonads, which can be purple or white depending on the population.

Distribution and habitat

Moon jellyfish are widely distributed in temperate and warmer coastal seas around the world. They are commonly found in shallow waters, estuaries, harbours, and near shore. They often appear in large groups and may wash ashore on beaches. In Canada, they occur in both Atlantic and Pacific coastal waters.

Life cycle and biology

The life cycle of moon jellyfish includes at least three stages: larva, attached polyp, and free-swimming medusa. The polyp stage can persist for many years under suitable conditions, while the adult medusa typically lives for months in the wild.

Ecology and human interactions

Moon jellyfish feed on plankton and other tiny drifting organisms, including small crustaceans, fish eggs, and larvae. Their sting is mild and generally not dangerous to humans. They are a common sight in aquarium displays.