Phyllorhiza punctata (Australian spotted jellyfish)
Phyllorhiza punctata (Australian spotted jellyfish) Gulf of Mexico. August 2000. Photo Dan Martin.

HEADLINE SCIENCE: Invasion of the Jellies

A gelatinous blob without a true brain, one that passively awaits prey to float into its mouth, seems harmless enough. But introduce millions of these blobs into prime spawning habitat and what you get is imminent catastrophe. This is the tone along the coast of the Gulf of Mexico, where jellyfish, native and nonnative alike, are amassing in unprecedented concentrations, posing a serious threat to the Gulf's ecology and large fisheries industry.

The spotted jellyfish (Phyllorhiza punctata), an Australian species first discovered in the Gulf in June, has besieged the waters of the barrier islands in the Mississippi Sound, virtually clearing the area of fish eggs and larvae. Normally six to eight inches in diameter, some individuals have reached nightmarish size, nearly two feet across, taking advantage of an ecosystem free from natural predators and parasites that would normally limit their populations. Farther offshore, masses of native moon jellyfish (Aurelia aurita) are devouring plankton, the base of the food chain.

Life Cycle of Jellies

As most animal populations exist in natural cycles of boom and bust, the jelly numbers may decline without human intervention, although scientists from Dauphin Island Sea Lab in Alabama are concerned that Phyllorhiza could survive the winter in the hardy polyp stage of development. If they do, they could permanently alter the food chain. This winter, the jelly polyps will be closely monitored.

Moon jellies are available for viewing in the Venoms exhibit at the California Academy of Sciences.

Life Cycle of Jellies
Aurelia aurita (moon jelly)
Pyllorhiza punctata
Aurelia aurita (Moon Jelly) in the Carribbean Sea. Photo by Dan Martin
Pyllorhiza punctata in the Gulf of Mexico. Photo by Dan Martin
Aurelia aurita
Aurelia aurita in the Gulf of Mexico. Photo by Brian Jones