Jellyfish have no  brains. They have no intentions, goals or cares. They live their lives carried by ocean currents, steered by the wind and waves, adrift in the world.

Their carefree existence, however, can make for a painful visit to the beach.

Purple flags were hoisted above Alabama beaches this week to warn swimmers of jellyfish in the water.

The gelatinous and sometimes difficult-to-spot creatures don't intend to sting beachgoers or even be carried to the shoreline.

"For many people, it is not worth staying out of the water, even when jellies are present," said aquarist Kindall Calhoun and educator Mendel Graeber of the Alabama Aquarium at Dauphin Island.

The only way to guarantee you will not be stung: stay out of the water.

"This is the only sure way to avoid being stung when jellies are abundant near shore — they are not easy to see and avoid," Calhoun and Graeber said.

Scientists at the Dauphin Island Sea Lab said, in fact, jellies don't even decide to sting. They just do when a fish or human happens to get in the way.

Jellyfish tentacles contain stinging cells called nematocysts. Those nematocysts contain toxic barbs that remain enclosed in the cells until they are ruptured by a physical force, such as a nearby fish or your leg brushing against the tentacle.

This cell rupture is a little like a bubble popping, and when this occurs, the barbs inside the popping cells are shot out, sometimes into a small fish that the jellyfish can eat, sometimes into an unfortunate swimmer.

While there have been many types of jellyfish documented in the Gulf Coast region, the list of species seen off Alabama's coast is small. Scientists have recorded moon jellies, sea nettles, cannonball jellies and mushroom jellies in nearby waters.

Most jellyfish that live in the northern Gulf of Mexico have a relatively mild sting, though some people might have a greater sensitivity than others, resulting in a more painful experience.

Those jellyfish species move in and out of nearby waters depending on the seasons, their life cycle and environmental conditions. Some species are spotted more often in warmer months while others drift in during cooler months.

During heavy rainfall, the rainwater may flush nutrients from the land, fertilizing algae in the water and causing a jellyfish population boom as the creatures gobble up the algae.

I GOT STUNG. NOW WHAT?

If you are stung, do not follow the medical advice of urban legends. Urinating on the sting or applying meat tenderizer are not good options, the scientists say.

"Meat tenderizer used to be a recommended treatment, but formula variations make this an unreliable approach now," Graeber said.

Tentacles can be removed by scraping a credit card (or similar item) along the skin to lift the tentacle without rupturing more cells. The stinging cells are triggered by physical force, not by the jellyfish, so the tentacles can still sting the without being attached to the body of the jellyfish.

If the sting is still painful, soak the affected area in hot water (about 110-113 degrees Fahrenheit) for 20-45 minutes. If the affected area remains painful, apply a corticosteroid/antihistamine cream.