Moon jellyfish (Aurelia labiata) are small, translucent invertebrates that inhabit the northeast Pacific Ocean and frequent the waters of the Salish Sea. They can be distinguished by four opaque half-circles on a bell and a 16-scalloped bell margin. Unlike most jellyfish, their tentacles are thin and short, extending around the circumference of the bell. These jellyfish can be seen throughout the summertime in the Salish Sea floating near the surface where the temperature of the water is warmer. They usually gather in large masses in harbors and coves. Moon jellyfish eat fish eggs and larvae, zooplankton, small crustaceans, and cladocerans, known as water fleas.

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Moon jellyfish are closely related in looks and genome to Aurelia aurita, another species of moon jellyfish commonly found in the Atlantic Ocean.
Moon jellyfish have a short lifespan, usually emerging in early spring, then spawning and dying by late summer or early fall.
In the Salish Sea, the highest concentrations of jellyfish are observed during the month of June. The moon jellyfish and the lion’s mane jellyfish are the most frequently sighted species.
Young moon jellyfish are called polyps and tend to attach to the undersides of docks where they can avoid predators and have ample room to grow. Millions of polyps can be attached to the underside of a dock at one time.
Jellyfish are viewed as a nuisance when unpredictable blooms spawn great quantities of jellyfish at once. Their high numbers can cause them to congest fishing nets, and even clog and shut down power plants. Studies have shown that jellyfish populations increase rapidly in warmer temperatures.With climate change raising oceanic temperatures, we may encounter even larger outbreaks of jellyfish around the world.

Moon Jellyfish Facts