Photo credit: Mathias Appel, https://flic.kr/p/xdENJ4
Australian Spotted Jellyfish
Report this Species!
If you believe you have found this species anywhere in Pennsylvania, please report your findings to iMapInvasives by submitting an observation record.
Species at a Glance
The Australian spotted jellyfish, also known as the floating bell, was introduced to North America from the Western Pacific Ocean. It is threatening large commercial fisheries in the Gulf of Mexico by feeding on the eggs and larvae of fish, crabs, and shrimp, and by clogging fishing nets. While mildly venomous, it does not pose a threat to humans who may come in contact with it.
Large with a somewhat flattened gelatinous bell that is clear or possibly tinted brown with many small white crystalline refractive spots close to the surface. The bell is usually 45-50 cm (18-20 in) in diameter, but there has been a maximum reported size of 62 cm (24 in) and a weight of 11 kg (25 lbs). The bell margin lacks tentacles and the central mouth area is ringed by eight, thick, highly branching oral arms that end with large brown bundles of stinging cells. From each oral arm hangs a long ribbon-like transparent appendage. Within its native range, and in certain introduced localities, the jellyfish is a deep brown color owning to the presence of symbiotic protozoans called zooxanthellae; however, the Gulf of Mexico populations do not host the zooxanthellae and lack the brown coloration.
This species may be confused with the moon jellyfish (Aurelia aurita) based on similar size, but the moon jelly can be easily distinguished by its transparent body and horseshoe-shaped gonads, which can be easily seen through the top of the bell. In other parts of the world, the Australian spotted jellyfish co-occurs with other mastigiid jellyfish, which are similar in appearance, including several species belonging to the genus Mastigias.
This coastal and estuarine jellyfish prefers warm temperate seas and is often aggregated in near-shore waters, swimming near the surface in murky waters of harbors and embayments.
While it’s unclear how the Australian spotted jellyfish was introduced from Australia, many believe that ship traffic brought the jellyfish to the Gulf of Mexico. Once introduced, natural ocean circulation processes further distributed it. For example, specimens were able to break off the Loop Current that circulates through the Gulf and individuals ended up in an eddy south of the Alabama and Florida panhandle.
The Australian spotted jellyfish has a wide native distribution in Australia and much of the Indo-Pacific, including the Philippines archipelago. Swarms of this jellyfish have been reported from east Texas to Florida in the Gulf of Mexico and along the Atlantic coastlines of Florida, South Carolina, and North Carolina.
Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.
This jellyfish threatens large commercial fisheries of shrimp and crab in the Gulf of Mexico. It is feared it will feed directly on the eggs and larvae of fish, crab, and shrimp, having serious economic implications for commercial fishing. One of its biggest economic impacts has been the clogging of shrimp nets, which has an estimated economic loss ranging in the millions of dollars. The Australian spotted jellyfish also damages boat intakes and fishing gear, and has caused the closure of productive areas to fishing activities.
Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).