Phyllorhiza punctata

Phyllorhiza punctata is a species of jellyfish, also known as the Australian spotted jellyfish or the White-spotted jellyfish. It is native to the southwestern Pacific, where it feeds primarily on various snail species. It's normal size is between 16 and 19 centimeters. They have only a mild venom and are not considered a threat to humans.

Since at least 2000, Phyllorhiza punctata has been found in large numbers in Gulf of Mexico. While it is not known how it was introduced to the region, it has been theorized that budding polyps may have attached themselves to ships, or gotten carried in a ship's ballast tank which was subesquently dumped in the Gulf. As an invasive species, it has become a threat to several species of shrimp. In Gulf waters, the medusae grow to unusually large size, upward of 60cm across.

The species has also been found in the waters off the Hawaiian Islands since at least 1945, but have not experienced the same type of massive population explosion found in the Caribbean and the Gulf of Mexico. The ecological impact of the species in those waters has not been determined. It has been spotted off the Southern California coast, but not confirmed.