Jellyfish have long been a danger of the sea, and many summer beach stories involve a tale of a painful encounter. Now, according to researchers, there will be plenty more stories to tell:  jellyfish numbers are increasing, and they are migrating to popular swimming areas. The increase in jellyfish numbers can be traced to overfishing of their natural predators such as tuna, swordfish, and sea turtles. At the same time, jellyfish have started massing closer to shore, possibly responding to warmer seas related to global warming dynamics.

Jellyfish are found in most oceans, (check out this map of common tourist locations with jellyfish), and the National Science Foundation recently released a detailed paper on “hot spots” of recent jellyfish blooms that can help  anticipate problems in specific locations.  Of particular concern is the amount of jellyfish near Spain and the surrounding Mediterranean region this summer. Not only have numbers of Mauve Stinger jellyfish been increasing every year (with 300 people stung in Barcelona over a few hours in 2008), but this summer many Portuguese Man-of-War have been spotted. (While not technically jellyfish, they cause very painful stings and can cause chest pain or muscle spasms.)  This problem is definitely spreading as shown by the large number of jellyfish warning signs popping up on the beaches of the UK this week.

The bottom line is: if you’re at a favorite beach and encounter jellyfish, you’ll  need to know what to do if you get stung. The first, if obvious, rule is to get out of the water. Flag down a bystander or lifeguard if the pain is making it difficult for you to move in to shore. Once on shore, rinse with salt water (fresh may be more painful), ice it,  but don’t rub it. Remove the tentacles with tweezers and gloved hands. A vinegar rinse can help prevent the release of toxins, particularly with box jellyfish and the Portuguese man-of war. For these two species, you should also contact a medical authority. Many experienced beach bums recommend applying shaving cream or a paste of baking soda/water and then shaving or scraping with a credit card to remove stingers.  If you’re heading to a jellyfish hotspot you may want to consider adding tweezers, vinegar, and shaving cream to your first aid kit. By the way, the urban myth of urinating(!) on stings is just that — it won’t do any good, and could make it worse.

Jellyfish are actually fascinating animals. You can visit the interactive special report put out by the NSF if you’re interested in learning more about them through pictures, videos, and fun facts.  Just keep your distance from them in the surf.

What’s your jellyfish story?