PANEREA, Italy -- Don't be fooled by the clear, beckoning sea -- Italy's waters are getting dangerous.
Even the most macho, muscle-bound hunks have been seen howling in pain as they hobble out of the surf this summer. And they are not shouting "shark!" -- they are wailing "jellyfish."Throngs of the slimy, translucent creatures have headed to the Mediterranean to bob around Italy's shores and torment bathers with their dangling tentacles, which scorch the skin at a mere brush.
Marine biologists have been searching for an explanation for the outbreak, but it is proving a tough one to solve.
"Some days there are jellyfish everywhere. It's become a bit of a hazard, especially for tourists, but no one knows where they're coming from," said a bar owner in Panarea who revealed the blistered scar of a recent sting across her leg.
From beaches near Portofino in the northwest to Sicily's idyllic island of Panarea, the sea creatures, which have no brain, heart or gills, have been lurking around since May.
It is not the first time this has happened. Last year fishermen in southern France complained that hordes of monster jellyfish were tearing holes in their nets, and the population has been strangely multiplying for the last eight years.
"Jellyfish often move in swarms, and population sizes vary, usually peaking over one to three years, after which they die back to more normal levels for reasons we don't really understand," said Steve Hay, a jellyfish expert at the Marine Laboratory in Aberdeen, Scotland.
Like a similar outbreak in the 1980s, the current swarm has stayed longer than welcome, leaving scientists scratching their heads. While little is known about these wobbly predators, scientists have some ideas.
"The blooming of jellyfish is due to many factors. For one, jellyfish will quickly take advantage of any change in food supply to increase in mass," said Kevin Raskoff, a jellyfish specialist at the Monterey Bay Aquarium Research Institute.
Jellyfish, which are more than 95 percent water, prey typically on zooplankton -- including other jellyfish, small fish and eggs, which they trap and stun in their tentacles. In some U.S. lakes, jellyfish have been known to multiply to many millions if their food supply expands.
"Jellyfish may have existed in another form for many years, and suddenly the conditions were ripe for a boom," said Martha Regester from Baltimore's aquarium.
While species vary, most start life as an egg on a mother's mouth waiting for a sperm to float by. Once fertilized, they become larvae, which grow into polyps, and it is in this form that they can remain for many years producing clones.
Eventually, polyps bud off young jellyfish, and in their adult or "medusa" form they live for a mere two to six months, usually dying in rough waters.
"Jellyfish are not good swimmers, and waves and currents will largely dictate where they end up. It also appears that extremely hot and dry weather favor them because there's less fresh water running into the bays," Regester said.
What swimming they do is through jet propulsion. While they cannot see as such, jellyfish can smell, taste and sense changes in light. So when a human brushes against the sensory hairs growing all over a jellyfish, stinging cells are ready to fire poison like a harpoon in defense, even if they are dead.
While some jellyfish like the Australian box jelly can kill a human in a matter of minutes, the predominant breed in the Mediterranean is the "pelagia noctiluca," which normally only burns a whip-like scar across the body.
But the snake-like venom of the noctiluca, which glows a purplish yellow in the sea at night, can cause life-threatening allergic reactions such as anaphylactic shock in rare cases.
No such cases have been reported this summer, and usually a quick dousing with alcohol or vinegar is enough to calm a sting from the jellyfish, which commonly measures 4 inches in diameter and has eight tentacles dangling below.
Scientists say bathers should not flee in horror but warm to the creatures, as they do some good. Besides providing shelter for sea life such as crabs and small fish, some jellyfish are used to treat certain cancers and heart disease.
"It's difficult to see their beauty when you're surrounded by the horrible little beasts," grimaced the Panarea bar owner.