Texas Invasive Species InstitutePhyllorhiza punctata
Australian Spotted Jellyfish
Class: Scyphozoa
Order: Rhizostomae
Family: Mastigiidae
Photographer: Micha L. Rieser
Source: Wikipedia.org
Description
Phyllorhiza punctata is a large jellyfish with a rounded and somewhat flattened gelatinous bell that is clear or possibly tinted brown with many small reflective areas that look like white spots. This spotted jellyfish averages about 18-20 inches in bell diameter but one was found to have around a 28 inch bell diameter off of the coast of North Carolina.
Though the original description published by von Lendenfeld in 1884 originally described Port Jackson, Australia as the ‘type’ locality, it actually occurs throughout the Indo-Pacific Ocean including the Philippine archipelago, Thailand and Japan.
Ecological Threat: In the Gulf, this invader has formed huge swarms in recent years. Each jellyfish can clear 50 cubic meters of water filled with plankton in one day. This makes dense aggregations of Australian Spotted jellyfish dangerous because they can alter food webs in the water column. Gulf fisheries have been affected, because Phyllorhiza punctata eat larval fish and compete with suspension feeding fish and shrimp for food, and jellyfish tend to clog fishing nets. The attached polyp stage of this species, which buds off juvenile jellyfish, could be transported to our region on ship hulls. With this jellyfish being found in California Waters over to Gulf of Mexico and Atlantic waters it is a threat to Texas's coastal ecosystems.
Biology: This is a true jellyfish that goes through the juvenile polyp stage and the adult medusa stage. Jellyfish can live for up to five years in the polyp stage and up to two years in the medusa stage. Like most jellyfish they feed on zooplankton, which is an important animal for all aquatic ecosystems. When found in warm waters these jellyfish flourish. They are mostly salt tolerant but low salinities may have a negative effect on the species. In times of low salinity these jellyfish exhibit loss of their zooxanthellae, which are symbiotic algae. Zooxanthellae use nutrients not vital to the jellyfish to create energy for the jellyfish via photosynthesis. Not all jellyfish have symbiotic algae and whenever the zooxanthellae are lost in low salinity waters it lowers to jellyfish’s ability to survive in nutrient poor waters.
They have only a mild sting and their venom isn’t toxic or a threat to humans. However, their ability to consume massive amounts of zooplankton makes them a threat to water column ecosystems all over the world.
History: The species has been found in the waters off the Hawaiian Islands since at least 1945 and in large numbers in the Gulf of Mexico since 2000. It has been theorized that budding polyps may have attached themselves to ships, or were carried in a ship's ballast tank which was subsequently dumped. As an invasive species, it has become a threat to several species of shrimp. In Gulf waters, the medusae grow to unusually large size, upwards of 24 inches across.
In July 2007 smallish individuals were seen in Bogue Sound much further north along the North Carolina coast and all the way south to Florida. It has also been spotted off the Southern California coast, but its presence there has not yet been confirmed.
U.S. Habitat: Warm seas and tend to aggregate in near-shore waters. Phyllorhiza punctata has become an issue in the Northern Gulf of Mexico near the Mississippi Sound affecting zooplankton levels. It is highly possible this jellyfish has started to occupy the region of the Gulf bordering Texas.
Distribution
Native Origin: West Pacific from Australia to Japan
U.S. Present: West Coast, Gulf of Mexico and Atlantic Coast near North Carolina
Management
In the Pacific region, there are snails that eat the budding polyp stage of the jellyfish but in the North American waters these snails are not present to keep the jellyfish populations lower. Besides knowing that low salinity causes Phyllorhiza punctata to lose it symbiotic algae, there isn’t much known on how to manage jellyfish populations; especially since they are found in wide open ocean areas. Capture and not killing any jellyfish caught can help lower the population, but there could be millions of them in one area and fishermen can only devote so much time to an animal that generates no revenue for them. Vigilant eyes on ocean waters and continual reports of Australian Spotted Jellyfish sighting can help estimate how many are within the Gulf of Mexico and further measures can be taken.
Text References
Mianzan HW and Cornelius PFS .1999. Cubomedusae and Scyphomedusae. In: BoltovskoyD(ed) South Atlantic Zooplankton, pp 513–559. Backhuys Publishers, Leiden,The Netherlands
Woodward, Susan L., and Joyce Ann. Quinn. 2011. Australian Spotted Jellyfish. Encyclopedia of Invasive Species: From Africanized Honey Bees to Zebra Mussels. Santa Barbara, CA: Greenwood. 45-47. Print.
Internet Sources
